Qualification parameters for captain selection in a search head cluster

ABSTRACT

Embodiments of the present disclosure provide solutions for determining an elected search head captain is unqualified for the position, identifying a more qualified search head, and transferring the captain position to the more qualified search head. A method is provided that includes referencing qualification parameters in an elected search head captain, determining whether the newly elected search head captain is qualified for the position based on the parameters, identifying a more qualified search head to be the search head captain if the newly elected search head captain is determined to be unqualified for the position, and transferring the position of captain to the more qualified search head. The qualification parameters may include, for example, a pre-determined static flag set by an administrator of the search environment, and configuration replication status that corresponds to the most recent configuration state of the search head as recorded by the previous search head captain.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit under 35 U.S.C. § 120 as a Continuation of U.S. application Ser. No. 15/582,441, filed Apr. 28, 2017, and entitled, “Intelligent Captain Selection For Disaster Recovery of Search Head Cluster,” and having attorney docket number SPLK-0011-01.01US. The entire contents of each of the above-listed applications is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Modern data centers often comprise thousands of hosts that operate collectively to service requests from even larger numbers of remote clients. During operation, components of these data centers can produce significant volumes of machine-generated data. The unstructured nature of much of this data has made it challenging to perform indexing and searching operations because of the difficulty of applying semantic meaning to unstructured data. As the number of hosts and clients associated with a data center continues to grow, processing large volumes of machine-generated data in an intelligent manner and effectively presenting the results of such processing continues to be priority.

In particular, where multiple users from a single institution or even multiple institutions access the same data sets, maintaining a consistent user experience across all instances and interfaces in real time presents a distinct challenge, particularly when components in the search environment go offline, due to network or system failures. Conventional approaches commonly use a designated search component, a so-called search head captain, to coordinate communication between members of the search environment. However, if the search head captain goes down, or otherwise needs to be transferred, selecting a qualified component to become the next coordinating component becomes a significant challenge.

SUMMARY

This Summary is provided to introduce a selection of concepts in a simplified form that is further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

To ensure the position of search head captain in a cluster of search heads in a search environment is filled by qualified candidates, embodiments of the present disclosure provide solutions for determining an elected search head captain is unqualified for the position, identifying a more qualified search head, and transferring the captain position to the more qualified search head. According to one or more embodiments of the present disclosure, a method is provided that includes referencing qualification parameters in a newly elected search head captain, determining whether the newly elected search head captain is qualified for the position based on the qualification parameters, identifying a more qualified search head to be the search head captain if the newly elected search head captain is determined to be unqualified for the position, and transferring the position of captain to the more qualified search head. The qualification parameters may include, for example, a pre-determined static flag set by an administrator of the search environment, and configuration replication status that corresponds to the most recent configuration state of the search head as recorded by the previous search head captain. By determining the qualifications of the current search head and transferring the leadership to a more qualified search head when the current search head is found to be unqualified, a threshold level of synchronization between the search heads of the search head cluster can be maintained.

According to a second embodiment, a shared data structure that stores, inter alia, the configuration replication status for each search head of a search head cluster is maintained. The shared data structure may be maintained by a search head captain for the search heads in the cluster by periodically updating the configuration replication status for each search head based on timestamps generated from a successful configuration replication between the search head and the search head captain.

According to a third embodiment of the present disclosure, a system is provided to track the configuration replication status of the search heads of a search head cluster, to determine a qualification of a search head for the position of search head captain, to identify a qualified search head for the position of search head captain, and to transfer the captaincy of the search head cluster to the qualified search head.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 illustrates a networked computer environment in which an embodiment may be implemented;

FIG. 2 illustrates a block diagram of an example data intake and query system in which an embodiment may be implemented;

FIG. 3 is a flow diagram that illustrates how indexers process, index, and store data received from forwarders in accordance with the disclosed embodiments;

FIG. 4 is a flow diagram that illustrates how a search head and indexers perform a search query in accordance with the disclosed embodiments;

FIG. 5 illustrates a scenario where a common customer ID is found among log data received from three disparate sources in accordance with the disclosed embodiments;

FIG. 6 illustrates a state diagram that illustrates an exemplary series of transfer of the position of captain in a search head cluster in accordance with the disclosed embodiments;

FIG. 7 is a flow diagram of an example process for selecting a search head captain in a search head cluster in accordance with the disclosed embodiments;

FIG. 8 is a flow diagram of an example process for managing captaincy qualification parameters for search heads of a search head cluster in accordance with the disclosed embodiments;

FIG. 9A illustrates a search screen in accordance with the disclosed embodiments;

FIG. 9B illustrates a data summary dialog that enables a user to select various data sources in accordance with the disclosed embodiments;

FIGS. 10A-10D illustrate a series of user interface screens for an example data model-driven report generation interface in accordance with the disclosed embodiments;

FIG. 11 illustrates an example search query received from a client and executed by search peers in accordance with the disclosed embodiments;

FIG. 12A illustrates a key indicators view in accordance with the disclosed embodiments;

FIG. 12B illustrates an incident review dashboard in accordance with the disclosed embodiments;

FIG. 12C illustrates a proactive monitoring tree in accordance with the disclosed embodiments;

FIG. 12D illustrates a user interface screen displaying both log data and performance data in accordance with the disclosed embodiments;

FIG. 13 illustrates a block diagram of an example cloud-based data intake and query system in which an embodiment may be implemented;

FIG. 14 illustrates a block diagram of an example data intake and query system that performs searches across external data systems in accordance with the disclosed embodiments;

FIGS. 15-17 illustrate a series of user interface screens for an example data model-driven report generation interface in accordance with the disclosed embodiments;

FIGS. 18-20 illustrate example visualizations generated by a reporting application in accordance with the disclosed embodiments;

DETAILED DESCRIPTION

Embodiments are described herein according to the following outline:

1.0. General Overview

2.0. Operating Environment

-   -   2.1. Host Devices     -   2.2. Client Devices     -   2.3. Client Device Applications     -   2.4. Data Server System     -   2.5. Data Ingestion         -   2.5.1. Input         -   2.5.2. Parsing         -   2.5.3. Indexing     -   2.6. Query Processing     -   2.7. Field Extraction         -   2.7.1. Search Head Cluster Environments         -   2.7.2. Intelligent Captain Selection     -   2.8. Example Search Screen     -   2.9. Data Modelling     -   2.10. Acceleration Techniques         -   2.10.1. Aggregation Technique         -   2.10.2. Keyword Index         -   2.10.3. High Performance Analytics Store         -   2.10.4. Accelerating Report Generation     -   2.11. Security Features     -   2.12. Data Center Monitoring     -   2.13. Cloud-Based System Overview     -   2.14. Searching Externally Archived Data         -   2.14.1. ERP Process Features

1.0. General Overview

Modern data centers and other computing environments can comprise anywhere from a few host computer systems to thousands of systems configured to process data, service requests from remote clients, and perform numerous other computational tasks. During operation, various components within these computing environments often generate significant volumes of machine-generated data. For example, machine data is generated by various components in the information technology (IT) environments, such as servers, sensors, routers, mobile devices, Internet of Things (IoT) devices, etc. Machine-generated data can include system logs, network packet data, sensor data, application program data, error logs, stack traces, system performance data, etc. In general, machine-generated data can also include performance data, diagnostic information, and many other types of data that can be analyzed to diagnose performance problems, monitor user interactions, and to derive other insights.

A number of tools are available to analyze machine data, that is, machine-generated data. In order to reduce the size of the potentially vast amount of machine data that may be generated, many of these tools typically pre-process the data based on anticipated data-analysis needs. For example, pre-specified data items may be extracted from the machine data and stored in a database to facilitate efficient retrieval and analysis of those data items at search time. However, the rest of the machine data typically is not saved and discarded during pre-processing. As storage capacity becomes progressively cheaper and more plentiful, there are fewer incentives to discard these portions of machine data and many reasons to retain more of the data.

This plentiful storage capacity is presently making it feasible to store massive quantities of minimally processed machine data for later retrieval and analysis. In general, storing minimally processed machine data and performing analysis operations at search time can provide greater flexibility because it enables an analyst to search all of the machine data, instead of searching only a pre-specified set of data items. This may enable an analyst to investigate different aspects of the machine data that previously were unavailable for analysis.

However, analyzing and searching massive quantities of machine data presents a number of challenges. For example, a data center, servers, or network appliances may generate many different types and formats of machine data (e.g., system logs, network packet data (e.g., wire data, etc.), sensor data, application program data, error logs, stack traces, system performance data, operating system data, virtualization data, etc.) from thousands of different components, which can collectively be very time-consuming to analyze. In another example, mobile devices may generate large amounts of information relating to data accesses, application performance, operating system performance, network performance, etc. There can be millions of mobile devices that report these types of information.

These challenges can be addressed by using an event-based data intake and query system, such as the SPLUNK® ENTERPRISE system developed by Splunk Inc. of San Francisco, Calif. The SPLUNK® ENTERPRISE system is the leading platform for providing real-time operational intelligence that enables organizations to collect, index, and search machine-generated data from various websites, applications, servers, networks, and mobile devices that power their businesses. The SPLUNK® ENTERPRISE system is particularly useful for analyzing data which is commonly found in system log files, network data, and other data input sources. Although many of the techniques described herein are explained with reference to a data intake and query system similar to the SPLUNK® ENTERPRISE system, these techniques are also applicable to other types of data systems.

In the SPLUNK® ENTERPRISE system, machine-generated data are collected and stored as “events”. An event comprises a portion of the machine-generated data and is associated with a specific point in time. For example, events may be derived from “time series data,” where the time series data comprises a sequence of data points (e.g., performance measurements from a computer system, etc.) that are associated with successive points in time. In general, each event can be associated with a timestamp that is derived from the raw data in the event, determined through interpolation between temporally proximate events having known timestamps, or determined based on other configurable rules for associating timestamps with events, etc.

In some instances, machine data can have a predefined format, where data items with specific data formats are stored at predefined locations in the data. For example, the machine data may include data stored as fields in a database table. In other instances, machine data may not have a predefined format, that is, the data is not at fixed, predefined locations, but the data does have repeatable patterns and is not random. This means that some machine data can comprise various data items of different data types and that may be stored at different locations within the data. For example, when the data source is an operating system log, an event can include one or more lines from the operating system log containing raw data that includes different types of performance and diagnostic information associated with a specific point in time.

Examples of components which may generate machine data from which events can be derived include, but are not limited to, web servers, application servers, databases, firewalls, routers, operating systems, and software applications that execute on computer systems, mobile devices, sensors, Internet of Things (IoT) devices, etc. The data generated by such data sources can include, for example and without limitation, server log files, activity log files, configuration files, messages, network packet data, performance measurements, sensor measurements, etc.

The SPLUNK® ENTERPRISE system uses flexible schema to specify how to extract information from the event data. A flexible schema may be developed and redefined as needed. Note that a flexible schema may be applied to event data “on the fly,” when it is needed (e.g., at search time, index time, ingestion time, etc.). When the schema is not applied to event data until search time it may be referred to as a “late-binding schema.”

During operation, the SPLUNK® ENTERPRISE system starts with raw input data (e.g., one or more system logs, streams of network packet data, sensor data, application program data, error logs, stack traces, system performance data, etc.). The system divides this raw data into blocks (e.g., buckets of data, each associated with a specific time frame, etc.), and parses the raw data to produce timestamped events. The system stores the timestamped events in a data store. The system enables users to run queries against the stored data to, for example, retrieve events that meet criteria specified in a query, such as containing certain keywords or having specific values in defined fields. As used herein throughout, data that is part of an event is referred to as “event data”. In this context, the term “field” refers to a location in the event data containing one or more values for a specific data item. As will be described in more detail herein, the fields are defined by extraction rules (e.g., regular expressions) that derive one or more values from the portion of raw machine data in each event that has a particular field specified by an extraction rule. The set of values so produced are semantically-related (such as IP address), even though the raw machine data in each event may be in different formats (e.g., semantically-related values may be in different positions in the events derived from different sources).

As noted above, the SPLUNK® ENTERPRISE system utilizes a late-binding schema to event data while performing queries on events. One aspect of a late-binding schema is applying “extraction rules” to event data to extract values for specific fields during search time. More specifically, the extraction rules for a field can include one or more instructions that specify how to extract a value for the field from the event data. An extraction rule can generally include any type of instruction for extracting values from data in events. In some cases, an extraction rule comprises a regular expression where a sequence of characters form a search pattern, in which case the rule is referred to as a “regex rule.” The system applies the regex rule to the event data to extract values for associated fields in the event data by searching the event data for the sequence of characters defined in the regex rule.

In the SPLUNK® ENTERPRISE system, a field extractor may be configured to automatically generate extraction rules for certain field values in the events when the events are being created, indexed, or stored, or possibly at a later time. Alternatively, a user may manually define extraction rules for fields using a variety of techniques. In contrast to a conventional schema for a database system, a late-binding schema is not defined at data ingestion time. Instead, the late-binding schema can be developed on an ongoing basis until the time a query is actually executed. This means that extraction rules for the fields in a query may be provided in the query itself, or may be located during execution of the query. Hence, as a user learns more about the data in the events, the user can continue to refine the late-binding schema by adding new fields, deleting fields, or modifying the field extraction rules for use the next time the schema is used by the system. Because the SPLUNK® ENTERPRISE system maintains the underlying raw data and uses late-binding schema for searching the raw data, it enables a user to continue investigating and learn valuable insights about the raw data.

In some embodiments, a common field name may be used to reference two or more fields containing equivalent data items, even though the fields may be associated with different types of events that possibly have different data formats and different extraction rules. By enabling a common field name to be used to identify equivalent fields from different types of events generated by disparate data sources, the system facilitates use of a “common information model” (CIM) across the disparate data sources (further discussed with respect to FIG. 5).

2.0. Operating Environment

FIG. 1 illustrates a networked computer system 100 in which an embodiment may be implemented. Those skilled in the art would understand that FIG. 1 represents one example of a networked computer system and other embodiments may use different arrangements.

The networked computer system 100 comprises one or more computing devices. These one or more computing devices comprise any combination of hardware and software configured to implement the various logical components described herein. For example, the one or more computing devices may include one or more memories that store instructions for implementing the various components described herein, one or more hardware processors configured to execute the instructions stored in the one or more memories, and various data repositories in the one or more memories for storing data structures utilized and manipulated by the various components.

In an embodiment, one or more client devices 102 are coupled to one or more host devices 106 and a data intake and query system 108 via one or more networks 104. Networks 104 broadly represent one or more LANs, WANs, cellular networks (e.g., LTE, HSPA, 3G, and other cellular technologies), and/or networks using any of wired, wireless, terrestrial microwave, or satellite links, and may include the public Internet.

2.1. Host Devices

In the illustrated embodiment, a system 100 includes one or more host devices 106. Host devices 106 may broadly include any number of computers, virtual machine instances, and/or data centers that are configured to host or execute one or more instances of host applications 114. In general, a host device 106 may be involved, directly or indirectly, in processing requests received from client devices 102. Each host device 106 may comprise, for example, one or more of a network device, a web server, an application server, a database server, etc. A collection of host devices 106 may be configured to implement a network-based service. For example, a provider of a network-based service may configure one or more host devices 106 and host applications 114 (e.g., one or more web servers, application servers, database servers, etc.) to collectively implement the network-based application.

In general, client devices 102 communicate with one or more host applications 114 to exchange information. The communication between a client device 102 and a host application 114 may, for example, be based on the Hypertext Transfer Protocol (HTTP) or any other network protocol. Content delivered from the host application 114 to a client device 102 may include, for example, HTML, documents, media content, etc. The communication between a client device 102 and host application 114 may include sending various requests and receiving data packets. For example, in general, a client device 102 or application running on a client device may initiate communication with a host application 114 by making a request for a specific resource (e.g., based on an HTTP request), and the application server may respond with the requested content stored in one or more response packets.

In the illustrated embodiment, one or more of host applications 114 may generate various types of performance data during operation, including event logs, network data, sensor data, and other types of machine-generated data. For example, a host application 114 comprising a web server may generate one or more web server logs in which details of interactions between the web server and any number of client devices 102 is recorded. As another example, a host device 106 comprising a router may generate one or more router logs that record information related to network traffic managed by the router. As yet another example, a host application 114 comprising a database server may generate one or more logs that record information related to requests sent from other host applications 114 (e.g., web servers or application servers) for data managed by the database server.

2.2. Client Devices

Client devices 102 of FIG. 1 represent any computing device capable of interacting with one or more host devices 106 via a network 104. Examples of client devices 102 may include, without limitation, smart phones, tablet computers, handheld computers, wearable devices, laptop computers, desktop computers, servers, portable media players, gaming devices, and so forth. In general, a client device 102 can provide access to different content, for instance, content provided by one or more host devices 106, etc. Each client device 102 may comprise one or more client applications 110, described in more detail in a separate section hereinafter.

2.3. Client Device Applications

In an embodiment, each client device 102 may host or execute one or more client applications 110 that are capable of interacting with one or more host devices 106 via one or more networks 104. For instance, a client application 110 may be or comprise a web browser that a user may use to navigate to one or more websites or other resources provided by one or more host devices 106. As another example, a client application 110 may comprise a mobile application or “app.” For example, an operator of a network-based service hosted by one or more host devices 106 may make available one or more mobile apps that enable users of client devices 102 to access various resources of the network-based service. As yet another example, client applications 110 may include background processes that perform various operations without direct interaction from a user. A client application 110 may include a “plug-in” or “extension” to another application, such as a web browser plug-in or extension.

In an embodiment, a client application 110 may include a monitoring component 112. At a high level, the monitoring component 112 comprises a software component or other logic that facilitates generating performance data related to a client device's operating state, including monitoring network traffic sent and received from the client device and collecting other device and/or application-specific information. Monitoring component 112 may be an integrated component of a client application 110, a plug-in, an extension, or any other type of add-on component. Monitoring component 112 may also be a stand-alone process.

In one embodiment, a monitoring component 112 may be created when a client application 110 is developed, for example, by an application developer using a software development kit (SDK). The SDK may include custom monitoring code that can be incorporated into the code implementing a client application 110. When the code is converted to an executable application, the custom code implementing the monitoring functionality can become part of the application itself.

In some cases, an SDK or other code for implementing the monitoring functionality may be offered by a provider of a data intake and query system, such as a system 108. In such cases, the provider of the system 108 can implement the custom code so that performance data generated by the monitoring functionality is sent to the system 108 to facilitate analysis of the performance data by a developer of the client application or other users.

In an embodiment, the custom monitoring code may be incorporated into the code of a client application 110 in a number of different ways, such as the insertion of one or more lines in the client application code that call or otherwise invoke the monitoring component 112. As such, a developer of a client application 110 can add one or more lines of code into the client application 110 to trigger the monitoring component 112 at desired points during execution of the application. Code that triggers the monitoring component may be referred to as a monitor trigger. For instance, a monitor trigger may be included at or near the beginning of the executable code of the client application 110 such that the monitoring component 112 is initiated or triggered as the application is launched, or included at other points in the code that correspond to various actions of the client application, such as sending a network request or displaying a particular interface.

In an embodiment, the monitoring component 112 may monitor one or more aspects of network traffic sent and/or received by a client application 110. For example, the monitoring component 112 may be configured to monitor data packets transmitted to and/or from one or more host applications 114. Incoming and/or outgoing data packets can be read or examined to identify network data contained within the packets, for example, and other aspects of data packets can be analyzed to determine a number of network performance statistics. Monitoring network traffic may enable information to be gathered particular to the network performance associated with a client application 110 or set of applications.

In an embodiment, network performance data refers to any type of data that indicates information about the network and/or network performance. Network performance data may include, for instance, a URL requested, a connection type (e.g., HTTP, HTTPS, etc.), a connection start time, a connection end time, an HTTP status code, request length, response length, request headers, response headers, connection status (e.g., completion, response time(s), failure, etc.), and the like. Upon obtaining network performance data indicating performance of the network, the network performance data can be transmitted to a data intake and query system 108 for analysis.

Upon developing a client application 110 that incorporates a monitoring component 112, the client application 110 can be distributed to client devices 102. Applications generally can be distributed to client devices 102 in any manner, or they can be pre-loaded. In some cases, the application may be distributed to a client device 102 via an application marketplace or other application distribution system. For instance, an application marketplace or other application distribution system might distribute the application to a client device based on a request from the client device to download the application.

Examples of functionality that enables monitoring performance of a client device are described in U.S. patent application Ser. No. 14/524,748, entitled “UTILIZING PACKET HEADERS TO MONITOR NETWORK TRAFFIC IN ASSOCIATION WITH A CLIENT DEVICE”, filed on 27 Oct. 2014, and which is hereby incorporated by reference in its entirety for all purposes.

In an embodiment, the monitoring component 112 may also monitor and collect performance data related to one or more aspects of the operational state of a client application 110 and/or client device 102. For example, a monitoring component 112 may be configured to collect device performance information by monitoring one or more client device operations, or by making calls to an operating system and/or one or more other applications executing on a client device 102 for performance information. Device performance information may include, for instance, a current wireless signal strength of the device, a current connection type and network carrier, current memory performance information, a geographic location of the device, a device orientation, and any other information related to the operational state of the client device.

In an embodiment, the monitoring component 112 may also monitor and collect other device profile information including, for example, a type of client device, a manufacturer and model of the device, versions of various software applications installed on the device, and so forth.

In general, a monitoring component 112 may be configured to generate performance data in response to a monitor trigger in the code of a client application 110 or other triggering application event, as described above, and to store the performance data in one or more data records. Each data record, for example, may include a collection of field-value pairs, each field-value pair storing a particular item of performance data in association with a field for the item. For example, a data record generated by a monitoring component 112 may include a “networkLatency” field (not shown in the Figure) in which a value is stored. This field indicates a network latency measurement associated with one or more network requests. The data record may include a “state” field to store a value indicating a state of a network connection, and so forth for any number of aspects of collected performance data.

2.4. Data Server System

FIG. 2 depicts a block diagram of an exemplary data intake and query system 108, similar to the SPLUNK® ENTERPRISE system. System 108 includes one or more forwarders 204 that receive data from a variety of input data sources 202, and one or more indexers 206 that process and store the data in one or more data stores 208. These forwarders and indexers can comprise separate computer systems, or may alternatively comprise separate processes executing on one or more computer systems.

Each data source 202 broadly represents a distinct source of data that can be consumed by a system 108. Examples of a data source 202 include, without limitation, data files, directories of files, data sent over a network, event logs, registries, etc.

During operation, the forwarders 204 identify which indexers 206 receive data collected from a data source 202 and forward the data to the appropriate indexers. Forwarders 204 can also perform operations on the data before forwarding, including removing extraneous data, detecting timestamps in the data, parsing data, indexing data, routing data based on criteria relating to the data being routed, and/or performing other data transformations.

In an embodiment, a forwarder 204 may comprise a service accessible to client devices 102 and host devices 106 via a network 104. For example, one type of forwarder 204 may be capable of consuming vast amounts of real-time data from a potentially large number of client devices 102 and/or host devices 106. The forwarder 204 may, for example, comprise a computing device which implements multiple data pipelines or “queues” to handle forwarding of network data to indexers 206. A forwarder 204 may also perform many of the functions that are performed by an indexer. For example, a forwarder 204 may perform keyword extractions on raw data or parse raw data to create events. A forwarder 204 may generate time stamps for events. Additionally or alternatively, a forwarder 204 may perform routing of events to indexers. Data store 208 may contain events derived from machine data from a variety of sources all pertaining to the same component in an IT environment, and this data may be produced by the machine in question or by other components in the IT environment.

2.5. Data Ingestion

FIG. 3 depicts a flow chart illustrating an example data flow performed by Data Intake and Query system 108, in accordance with the disclosed embodiments. The data flow illustrated in FIG. 3 is provided for illustrative purposes only; those skilled in the art would understand that one or more of the steps of the processes illustrated in FIG. 3 may be removed or the ordering of the steps may be changed. Furthermore, for the purposes of illustrating a clear example, one or more particular system components are described in the context of performing various operations during each of the data flow stages. For example, a forwarder is described as receiving and processing data during an input phase; an indexer is described as parsing and indexing data during parsing and indexing phases; and a search head is described as performing a search query during a search phase. However, other system arrangements and distributions of the processing steps across system components may be used.

2.5.1. Input

At block 302, a forwarder receives data from an input source, such as a data source 202 shown in FIG. 2. A forwarder initially may receive the data as a raw data stream generated by the input source. For example, a forwarder may receive a data stream from a log file generated by an application server, from a stream of network data from a network device, or from any other source of data. In one embodiment, a forwarder receives the raw data and may segment the data stream into “blocks”, or “buckets,” possibly of a uniform data size, to facilitate subsequent processing steps.

At block 304, a forwarder or other system component annotates each block generated from the raw data with one or more metadata fields. These metadata fields may, for example, provide information related to the data block as a whole and may apply to each event that is subsequently derived from the data in the data block. For example, the metadata fields may include separate fields specifying each of a host, a source, and a source type related to the data block. A host field may contain a value identifying a host name or IP address of a device that generated the data. A source field may contain a value identifying a source of the data, such as a pathname of a file or a protocol and port related to received network data. A source type field may contain a value specifying a particular source type label for the data. Additional metadata fields may also be included during the input phase, such as a character encoding of the data, if known, and possibly other values that provide information relevant to later processing steps. In an embodiment, a forwarder forwards the annotated data blocks to another system component (typically an indexer) for further processing.

The SPLUNK® ENTERPRISE system allows forwarding of data from one SPLUNK® ENTERPRISE instance to another, or even to a third-party system. SPLUNK® ENTERPRISE system can employ different types of forwarders in a configuration.

In an embodiment, a forwarder may contain the essential components needed to forward data. It can gather data from a variety of inputs and forward the data to a SPLUNK® ENTERPRISE server for indexing and searching. It also can tag metadata (e.g., source, source type, host, etc.).

Additionally or optionally, in an embodiment, a forwarder has the capabilities of the aforementioned forwarder as well as additional capabilities. The forwarder can parse data before forwarding the data (e.g., associate a time stamp with a portion of data and create an event, etc.) and can route data based on criteria such as source or type of event. It can also index data locally while forwarding the data to another indexer.

2.5.2. Parsing

At block 306, an indexer receives data blocks from a forwarder and parses the data to organize the data into events. In an embodiment, to organize the data into events, an indexer may determine a source type associated with each data block (e.g., by extracting a source type label from the metadata fields associated with the data block, etc.) and refer to a source type configuration corresponding to the identified source type. The source type definition may include one or more properties that indicate to the indexer to automatically determine the boundaries of events within the data. In general, these properties may include regular expression-based rules or delimiter rules where, for example, event boundaries may be indicated by predefined characters or character strings. These predefined characters may include punctuation marks or other special characters including, for example, carriage returns, tabs, spaces, line breaks, etc. If a source type for the data is unknown to the indexer, an indexer may infer a source type for the data by examining the structure of the data. Then, it can apply an inferred source type definition to the data to create the events.

At block 308, the indexer determines a timestamp for each event. Similar to the process for creating events, an indexer may again refer to a source type definition associated with the data to locate one or more properties that indicate instructions for determining a timestamp for each event. The properties may, for example, instruct an indexer to extract a time value from a portion of data in the event, to interpolate time values based on timestamps associated with temporally proximate events, to create a timestamp based on a time the event data was received or generated, to use the timestamp of a previous event, or use any other rules for determining timestamps.

At block 310, the indexer associates with each event one or more metadata fields including a field containing the timestamp (in some embodiments, a timestamp may be included in the metadata fields) determined for the event. These metadata fields may include a number of “default fields” that are associated with all events, and may also include one more custom fields as defined by a user. Similar to the metadata fields associated with the data blocks at block 304, the default metadata fields associated with each event may include a host, source, and source type field including or in addition to a field storing the timestamp.

At block 312, an indexer may optionally apply one or more transformations to data included in the events created at block 306. For example, such transformations can include removing a portion of an event (e.g., a portion used to define event boundaries, extraneous characters from the event, other extraneous text, etc.), masking a portion of an event (e.g., masking a credit card number), removing redundant portions of an event, etc. The transformations applied to event data may, for example, be specified in one or more configuration files and referenced by one or more source type definitions.

2.5.3. Indexing

At blocks 314 and 316, an indexer can optionally generate a keyword index to facilitate fast keyword searching for event data. To build a keyword index, at block 314, the indexer identifies a set of keywords in each event. At block 316, the indexer includes the identified keywords in an index, which associates each stored keyword with reference pointers to events containing that keyword (or to locations within events where that keyword is located, other location identifiers, etc.). When an indexer subsequently receives a keyword-based query, the indexer can access the keyword index to quickly identify events containing the keyword.

In some embodiments, the keyword index may include entries for name-value pairs found in events, where a name-value pair can include a pair of keywords connected by a symbol, such as an equals sign or colon. This way, events containing these name-value pairs can be quickly located. In some embodiments, fields can automatically be generated for some or all of the name-value pairs at the time of indexing. For example, if the string “dest=10.0.1.2” is found in an event, a field named “dest” may be created for the event, and assigned a value of “10.0.1.2”.

At block 318, the indexer stores the events with an associated timestamp in a data store 208. Timestamps enable a user to search for events based on a time range. In one embodiment, the stored events are organized into “buckets,” where each bucket stores events associated with a specific time range based on the timestamps associated with each event. This may not only improve time-based searching, but also allows for events with recent timestamps, which may have a higher likelihood of being accessed, to be stored in a faster memory to facilitate faster retrieval. For example, buckets containing the most recent events can be stored in flash memory rather than on a hard disk.

Each indexer 206 may be responsible for storing and searching a subset of the events contained in a corresponding data store 208. By distributing events among the indexers and data stores, the indexers can analyze events for a query in parallel. For example, using map-reduce techniques, each indexer returns partial responses for a subset of events to a search head that combines the results to produce an answer for the query. By storing events in buckets for specific time ranges, an indexer may further optimize data retrieval process by searching buckets corresponding to time ranges that are relevant to a query.

Moreover, events and buckets can also be replicated across different indexers and data stores to facilitate high availability and disaster recovery as described in U.S. patent application Ser. No. 14/266,812, emitted “SITE-BASED SEARCH AFFINITY”, filed on 30 Apr. 2014, and in U.S. patent application Ser. No. 14/266,817, entitled “MULTI-SITE CLUSTERING”, also filed on 30 Apr. 2014, each of which is hereby incorporated by reference in its entirety for all purposes.

2.6. Query Processing

FIG. 4 is a flow diagram that illustrates an exemplary process that a search head and one or more indexers may perform during a search query. At block 402, a search head receives a search query from a client. At block 404, the search head analyzes the search query to determine what portion(s) of the query can be delegated to indexers and what portions of the query can be executed locally by the search head. At block 406, the search head distributes the determined portions of the query to the appropriate indexers. In an embodiment, a search head cluster may take the place of an independent search head where each search head in the search head cluster coordinates with peer search heads in the search head cluster to schedule jobs, replicate search results, update configurations, fulfill search requests, etc. In an embodiment, the search head (or each search head) communicates with a master node (also known as a cluster master, not shown in Fig.) that provides the search head with a list of indexers to which the search head can distribute the determined portions of the query. The master node maintains a list of active indexers and can also designate which indexers may have responsibility for responding to queries over certain sets of events. A search head may communicate with the master node before the search head distributes queries to indexers to discover the addresses of active indexers.

At block 408, the indexers to which the query was distributed, search data stores associated with them for events that are responsive to the query. To determine which events are responsive to the query, the indexer searches for events that match the criteria specified in the query. These criteria can include matching keywords or specific values for certain fields. The searching operations at block 408 may use the late-binding schema to extract values for specified fields from events at the time the query is processed. In an embodiment, one or more rules for extracting field values may be specified as part of a source type definition. The indexers may then either send the relevant events back to the search head, or use the events to determine a partial result, and send the partial result back to the search head.

At block 410, the search head combines the partial results and/or events received from the indexers to produce a final result for the query. This final result may comprise different types of data depending on what the query requested. For example, the results can include a listing of matching events returned by the query, or some type of visualization of the data from the returned events. In another example, the final result can include one or more calculated values derived from the matching events.

The results generated by the system 108 can be returned to a client using different techniques. For example, one technique streams results or relevant events back to a client in real-time as they are identified. Another technique waits to report the results to the client until a complete set of results (which may include a set of relevant events or a result based on relevant events) is ready to return to the client. Yet another technique streams interim results or relevant events back to the client in real-time until a complete set of results is ready, and then returns the complete set of results to the client. In another technique, certain results are stored as “search jobs” and the client may retrieve the results by referring the search jobs.

The search head can also perform various operations to make the search more efficient. For example, before the search head begins execution of a query, the search head can determine a time range for the query and a set of common keywords that all matching events include. The search head may then use these parameters to query the indexers to obtain a superset of the eventual results. Then, during a filtering stage, the search head can perform field-extraction operations on the superset to produce a reduced set of search results. This speeds up queries that are performed on a periodic basis.

2.7. Field Extraction

The search head 210 allows users to search and visualize event data extracted from raw machine data received from homogenous data sources. It also allows users to search and visualize event data extracted from raw machine data received from heterogeneous data sources. The search head 210 includes various mechanisms, which may additionally reside in an indexer 206, for processing a query. Splunk Processing Language (SPL), used in conjunction with the SPLUNK® ENTERPRISE system, can be utilized to make a query. SPL is a pipelined search language in which a set of inputs is operated on by a first command in a command line, and then a subsequent command following the pipe symbol “|” operates on the results produced by the first command, and so on for additional commands. Other query languages, such as the Structured Query Language (“SQL”), can be used to create a query.

In response to receiving the search query, search head 210 uses extraction rules to extract values for the fields associated with a field or fields in the event data being searched. The search head 210 obtains extraction rules that specify how to extract a value for certain fields from an event. Extraction rules can comprise regex rules that specify how to extract values for the relevant fields. In addition to specifying how to extract field values, the extraction rules may also include instructions for deriving a field value by performing a function on a character string or value retrieved by the extraction rule. For example, a transformation rule may truncate a character string, or convert the character string into a different data format. In some cases, the query itself can specify one or more extraction rules.

The search head 210 can apply the extraction rules to event data that it receives from indexers 206. Indexers 206 may apply the extraction rules to events in an associated data store 208. Extraction rules can be applied to all the events in a data store, or to a subset of the events that have been filtered based on some criteria (e.g., event time stamp values, etc.). Extraction rules can be used to extract one or more values for a field from events by parsing the event data and examining the event data for one or more patterns of characters, numbers, delimiters, etc., that indicate where the field begins and, optionally, ends.

FIG. 5 illustrates an example of raw machine data received from disparate data sources. In this example, a user submits an order for merchandise using a vendor's shopping application program 501 running on the user's system. In this example, the order was not delivered to the vendor's server due to a resource exception at the destination server that is detected by the middleware code 502. The user then sends a message to the customer support 503 to complain about the order failing to complete. The three systems 501, 502, and 503 are disparate systems that do not have a common logging format. The order application 501 sends log data 504 to the SPLUNK® ENTERPRISE system in one format, the middleware code 502 sends error log data 505 in a second format, and the support server 503 sends log data 506 in a third format.

Using the log data received at one or more indexers 206 from the three systems the vendor can uniquely obtain an insight into user activity, user experience, and system behavior. The search head 210 allows the vendor's administrator to search the log data from the three systems that one or more indexers 206 are responsible for searching, thereby obtaining correlated information, such as the order number and corresponding customer ID number of the person placing the order. The system also allows the administrator to see a visualization of related events via a user interface. The administrator can query the search head 210 for customer ID field value matches across the log data from the three systems that are stored at the one or more indexers 206. The customer ID field value exists in the data gathered from the three systems, but the customer ID field value may be located in different areas of the data given differences in the architecture of the systems—there is a semantic relationship between the customer ID field values generated by the three systems. The search head 210 requests event data from the one or more indexers 206 to gather relevant event data from the three systems. It then applies extraction rules to the event data in order to extract field values that it can correlate. The search head may apply a different extraction rule to each set of events from each system when the event data format differs among systems. In this example, the user interface can display to the administrator the event data corresponding to the common customer ID field values 507, 508, and 509, thereby providing the administrator with insight into a customer's experience.

Note that query results can be returned to a client, a search head, or any other system component for further processing. In general, query results may include a set of one or more events, a set of one or more values obtained from the events, a subset of the values, statistics calculated based on the values, a report containing the values, or a visualization, such as a graph or chart, generated from the values.

2.7.1. Search Head Cluster Environments

A search environment such as the data intake and query system 106 described above with respect to FIG. 2 may be implemented across multiple search heads 204. For example, implementations may include a cluster of multiple search heads accessible by a number of clients over a network. The search heads of the search head cluster may be, for example, server devices located at one or more sites, each site being geographically remote from the other site (e.g., in different cities). According to various embodiments, all of the search heads may be located at a single site, at least two of the search heads are located at a single site and at least one other of the search heads of the cluster is located at a different site, or each search head of the cluster is located at a different site.

Each of the search heads in the search head cluster may receive instructions to perform tasks from the clients on behalf of one or more users. For example, one of the search heads may receive a request from one of the clients to perform a search-related activity, such as a map-reduce search and/or a search using late-binding schema. In response to receiving the request to perform the search-related activity, the search head may perform the search.

According to embodiments of the present disclosure, the search heads may receive instructions from the clients to perform a knowledge object customization (i.e., a customization of a search-related and/or visualization-related configuration). A customization may include any action relating to a knowledge object, such as, for example, the deletion, creation, modification, change, or update of a knowledge object. A knowledge object is a configuration relating to search and/or visualization activity that is permissible and controlled via an access control layer of the system that is customizable by a user. Exemplary knowledge objects include, but are not limited to, a saved search, an event type, a transaction, a tag, a field extraction, a field transform, a lookup, a workflow action, a search command, a view, and late-binding schema. Although various exemplary knowledge objects are described below, it is noted that other knowledge objects (search-related or visualization-related configurations) may be customized in accordance with embodiments of the present disclosure.

A view is a knowledge object representing a customizable user interface accessible by a user. Dashboards and forms are examples of views. A view may be built from user interface components such as search boxes, fields, charts, tables, and lists. A view may be permissible and may be applied to specific application. A dashboard may be a static or dynamic (e.g., real-time) visualization of data. In an embodiment, a view may defined via user-specified HTML, “custom” XML formats, or the like.

A saved search is a knowledge object representing a search that has been made available for later use. For example, searches may be saved for producing a report, an alert or a dashboard panel.

An event type is a knowledge object that enables a user to categorize and label all indexed events that match a specified search string (e.g., a search query or search criteria). An event type may have a name and an associated search query or search criteria. A user may create an event type directly or use a device to identify and create an event type. For example, the user may use a device such as a typelearner (i.e., a utility that helps a user create event types, examines events resulting from a search, and suggests event types), an event type finder (i.e., a ‘findtypes’ command may be appended to a search to cause the search results to display as a breakdown of the most common groups of events found in the search results), or an event type builder (i.e., a utility or tool configured to dynamically create event types based on an analysis of a selected event).

A transaction is a knowledge object representing a group of conceptually-related events that span time. For example, events grouped together by a transaction often represent a complex, multistep business-related activity, such as all events related to a single hotel customer reservation session, or a customer session on a retail website. A user may use a ‘transaction’ command to find transactions based on a transaction definition (e.g., a transaction definition created by the user ad hoc) or to locate transactions based on a previously configured transaction type. In an embodiment, boundaries for transactions may be explicitly timespan-related, such as, for example, a transaction definition that requires that the first and last events in the transaction be no more than 30 seconds apart and the events within the transaction be no more than 5 seconds apart. In an embodiment, transaction boundaries may be defined without explicitly setting maximum timespans or event pauses. For example, a user may define a transaction for an online store called “item purchase” that looks for groups of events that share the same ‘sessionid’ and ‘clientip’ field values, have a starting event with the string “signon”, and an ending event with the string “purchase.” This exemplary transaction produces grouping of events that spans time.

In an embodiment, a tag is a knowledge object that enables a user to efficiently search for events that contain particular field values. In an embodiment, a user can assign one or more tags to any field/value combination, including, for example, event types, hosts, sources, and source types. In an embodiment, tags enable the user to track abstract field values like IP addresses or ID numbers. For example, a user may have a number of field values related to the user's home office, including an IP address such as 192.168.1.2. In this example, the user may tag these values “homeoffice” and then perform a search on “tag=homeoffice” to identify the events with field values that have the homeoffice tag.

In an embodiment, tags enable a user to group sets of related field values together. For example, if a user has two hosts that relate to the same computing device, the user may assign the two computing devices the same tag to allow the user to search on events coming from both hosts using the common tag.

In an embodiment, tags enable a user to assign extracted fields multiple tags that reflect different aspects of their identity. Accordingly, the user may create tag-based searches that use Boolean operators to narrow down on specific event sets.

In an embodiment, a field extraction is a knowledge object representing both a process by which fields are extracted from event data and the results of the extraction process (i.e., extracted fields). In an example, field extraction may take place either before events are indexed (e.g., in the case of default and indexed fields) or after event indexing (e.g., in the case of search fields). In an embodiment, a set of default fields may be automatically extracted for each indexed event. In an example, a user may “create” additional “custom” fields by defining additional index-time and search-time field extractions. A user may perform manual field extraction through the use of search commands, an extraction tool (e.g., interactive field extractor configured to enable a user to create custom fields dynamically while searching), and configuration files. A late-binding schema includes such field extractions, as each one may define a particular field and how to determine a value for the field from the events for which the field is defined.

In an embodiment, a transform or field transform is a knowledge object representing a transformation of an event. For example, a field transform may be used for an advanced type of search-time field extraction wherein a user wants to perform one or more of the following: (i) use the same regular expression across multiple source types, sources, or hosts; (ii) perform special formatting on the extracted field values; and (iii) extract fields from the values of another key field. In an embodiment, a transform may be involved in the setup of custom index-time field extractions. In an embodiment, a user may create transforms that mask sensitive data in events, such as customer credit card numbers. A transform may be involved in the creation of a lookup, as well as overrides of default host and source type values. In an additional example, a transform may be used to route event data to alternate indexes and forward raw event data to a third-party system.

In an embodiment, a lookup is a knowledge object that enables the addition of fields and related values to search results based on field matching (e.g., using a CSV table or a Python script). For example, a user may use a lookup to perform DNS or reverse DNS lookups on IP addresses or host names in the user's data. In an embodiment, a lookup may be incorporated into a dashboard or other application views presented by the system.

In an embodiment, a workflow action is a knowledge object that enables interactions between indexed fields in events and other web resources, including external web resources. For example, a workflow action may be defined to be associated with an IP address field in a user's search results or used to perform an external WHOIS lookup based on a particular value of that field in a specific event. In another example, a workflow action may be defined to use the field values in an HTTP error event to create a new entry in an external issue tracking system. In a further example, a workflow action may be defined to perform an external search (e.g., using a third party search engine or other web application) on the value of a field in an event. In another example, a workflow action may be defined to launch secondary searches that use one or more field values from selected events.

In an embodiment, a workflow action may be defined that is targeted to events that contain a particular field or set of fields, or which belong to a specific event type. A workflow action may be defined to open either in the current window or a new one when selected. In an embodiment, a workflow action may appear in field menus, event menus, or both (e.g., in search results).

In an embodiment, a search command or command is a knowledge object representing an element of search language used to interact with data maintained by the system. The search language may define many commands that allow a user to interact with the system and refine and modify search results. Examples of search commands include, but are not limited to, “stats,” “sort,” and “where”. In an embodiment, a user may expand upon the system's default search language by creating custom search commands that carry out specialized interactions.

In an embodiment, a configuration file (also referred to as a “conf file”) is a file containing system configuration information including, but not limited to, knowledge objects and knowledge objects customizations. In an embodiment, a search head writes configuration settings (e.g., knowledge object customizations) into its respective configuration file stored in the local data store of the individual search head.

In an embodiment, configuration replication is performed to synchronize the data structures of the multiple configuration files of the individual search heads across the cluster of search heads such that changes (e.g., user-initiated knowledge object customizations) made on one search head are applied on all search heads in the cluster. A user interface enabling a user to perform search-related activities, submit knowledge object customizations and interact with the search heads of the cluster may be provided. Advantageously, knowledge object customization and corresponding change or alteration to an individual configuration file of one search head may be presented to a user via the user interface of another search head in the cluster.

Knowledge object customizations made via the user interface associated with an individual search head (e.g., a Command Line Interface (CLI), a Representational State Transfer (REST) application programming interface (API), etc.) are journaled or recorded in a journal maintained in a local data store 1330 of the individual search head. In an embodiment, the journal is in-memory or on-disk and stored in the local data store 1330 repository including a history of knowledge object customizations (e.g., a list of recent configuration customization operations) performed by the corresponding search head, wherein each knowledge object customization is recorded as a journal entry. For example, each journal entry includes information relating to the knowledge object customization, including, but not limited to, a knowledge object location (e.g., user/application context, asset type, asset name, etc.), a knowledge object customization type or action (e.g., creation, modification, move, edit, remove, delete, share, change permissions, etc.), and a knowledge object customization payload (e.g., a key-value pair relating to the creation of a new knowledge object customization, a new location relating to a moving of a knowledge object customization, a new access control list relating to a sharing/permission change).

A knowledge object customization made by an individual search head may be recorded as a journal entry in the journal stored in the local data store of the individual search head. The individual search head writes the knowledge object customization to its local configuration file stored in the local data store.

During a synchronization phase including a “pull” stage and a “push” stage, an individual search head communicates with the search head leader, as described in detail below. During the “pull” stage, the individual search head receives any knowledge object customization updates from the search head leader. During the “push” stage, the individual search head sends any new journal entries to the search head leader. In an embodiment, the new journal entries include any journal entries that have not yet been sent to the search head leader.

2.7.2. Intelligent Captain Selection

In one or more embodiments, one of the search heads of a search head cluster is elected as the “leader” or captain of the cluster. In an embodiment, the other search heads in the cluster engage in intra-cluster communications exclusively with the search head captain (i.e., there is no follower-to-follower search head communication). Each search head may be either in a captain state or a follower state. In the captain state, the search head is responsible for synchronizing the knowledge object customizations across the cluster of search heads. In the follower state, each individual search heads receives updates regarding knowledge object customizations performed by other search heads in the cluster and sends updates regarding knowledge object customizations performed by the individual search head.

On occasion, the role of search head captain is transferred to another search head in the cluster. This situation can arise, for example, due to deteriorating network conditions, system failure, insufficient computing capability, or other similar circumstances that compromise the current search head captain's ability to coordinate and replicate configurations (knowledge object customizations) between the other search heads. To ensure a captain of the search head is available to coordinate configuration replication as much as possible, each search head also implements a captain-response timer that is refreshed whenever a communication is received from the search head captain, and counts down whenever a communication is sent from the search head and a response (e.g., acknowledgement, configuration replication) is not received from the current captain. When the timer is exhausted, the search head initiates the election protocol, nominating itself for the position of captain.

According to an embodiment, transferal of leadership is performed through an election protocol initiated by one or more search heads of the search head cluster. The election protocol may include, for example, a self-nomination by a search head of the cluster for the position of captain and a request for votes from the other search heads. A voting search head gives its vote if communication between the nominated search head and the voting search head is possible. If a nominated search head receives votes from a majority of the other search heads, a consensus is reached and the search head becomes the captain of the cluster until the next election cycle. In one or more embodiments, the election protocol may be performed by an election module, with an instance of the election module executing in each search head of the cluster.

However, a lack of a response from the current acting captain may not always be due to the capability of the captain being compromised. For example, when the search head itself experiences a system or network failure, the latency of communications between the search head and captain may also exceed the duration of the timer and cause the captain-response time to expire. In some instances, this may cause the search head to miss multiple configuration replication attempts from the search head captain before the search head is brought back online, further resulting in the search head being de-synchronized from the captain (and other search heads in the cluster by extension).

Ordinarily, the search head can be re-synchronized by comparing the latest configuration entry in the search head with the journal entries in the search head captain, establishing a baseline (i.e., the last common journal entry), and replicating all journal entries in the search head captain after the baseline to the search head, and vice versa. However, journals are statically sized, and older journal entries can be deleted as new journal entries are appended to the journal when the number of entries exceeds the size of the journal. If the search head is offline or a prolonged period of time elapses before communication capabilities are restored, or if the frequency of journal updates is high, the last journal entry in the search head may no longer correspond to any journal entry stored in the journal of the search head captain. A common baseline cannot therefore be established, and synchronization between the search head and the other search heads of the cluster may no longer be possible without manual intervention by a system administrator.

Under these circumstances, the de-synchronized search head may initiate the election protocol (due to its captain-response timer expiring). If communication with at least a majority of the other search heads is reestablished, the de-synchronized search head may still receive enough votes to become the new search head captain. This is undesirable due to the de-synchronization with the other member search heads of the cluster and would cause a reversion to the latest journal state of the de-synchronized search head across the other members if uncorrected.

According to embodiments, this situation is prevented by requiring the new search head captain to verify its own qualification for the captain role by referencing a data structure (such as a lookup table) that stores continuously updated metadata corresponding to interactions between search head captains and individual search heads. According to these embodiments, each time the search head member becomes the captain of the cluster, the search head member references the lookup table to determine its own qualification for the position of captain based on configuration replication status as updated by the previous search head captain. In still further embodiments, each search head member may also be pre-selected as a preferred captain (e.g., by a system administrator). A search head member may be pre-selected to be a preferred captain based on, for example, a locality of the search head member, or the computing resources (processing capability, available memory) available to the search head member. If the new search head captain is unqualified based on its configuration replication status (or if otherwise pre-selected as not a preferred captain), the new search head captain identifies a more qualified search head member in the cluster and transfers captaincy to that member. In one or more embodiments, transferal of captaincy to another member may be performed by prompting the member to initiate an election for a newer election term.

FIG. 6 depicts a state diagram 600 that illustrates the transferal of the captain role between various members of a search cluster over time. As depicted in FIG. 6, at time A, a three search head cluster (search head 210 a, 210 b, 210 c) is depicted with functioning communication channels, with search head 210 a the current captain in the cluster. At time B, communication channels between search head 210 c and both 210 a and 210 b have been compromised, via network or system failure in 210 c, for example. The captain-response timer 601 in search head 210 c begins to countdown after one or more attempts to communicate configuration replications with search head 210 a (the current captain) are unsuccessful or unreturned.

At time C, the search head 210 c comes back online or otherwise restores communication capability with at least one other search head (210 b) by the time the captain-response timer 601 expires. Search head 210 c initiates an election protocol, such as the Raft Consensus Algorithm, nominating itself for the position of captain. Since communication has been restored between search head 210 c and at least search head 210 b, 210 b submits a vote for 210 c in the election protocol. With a majority of votes in the cluster (its own and the vote from search head 210 b), search head 210 c assumes the position of captain of the search cluster at time D.

Once search head 210 c becomes the captain of the search cluster, search head 210 c references, at time E, a data structure 603 maintained by all acting search head captains during their captaincy that stores the most recent configuration status of all search heads in the cluster. In one or more embodiments, the data structure 603 may be implemented as a lookup table or key-value store accessible to each search head member. Each time a configuration is successfully replicated in a particular search head, the current acting captain in the cluster updates the configuration replication status of that search head in the data structure. According to further embodiments, whenever a configuration is replicated from the captain to a member search head, the search head sends a flag to the captain that confirms the successful replication. The captain determines the global unique identifier (GUID) of the configuration replicated and a timestamp of the replication and updates the entry in the data structure corresponding to the member search head with the GUIID and timestamp information of the configuration. According to still further embodiments, the search head may send the confirmation flag as part as a scheduled communication performed via a persistent communication channel (such as a heartbeat thread) maintained between the search head captain and each member search head.

Search head 210 c is thus able to see whether its own configuration replication status is synchronized with the other search head members in the cluster. If the new captain (search head 210 c) determines its own qualification to be captain based on its configuration replication status, it stays as the captain (search head 210 c). However, if the new captain determines that it is not qualified to be captain based on its own configuration replication status relative to the configuration replication status of the other search head members of the cluster, the current search head captain (search head 210 c) prompts a more qualified member in the cluster to initiate its own election protocol (e.g., by causing the captain-response timer 601 in the more qualified member to immediately expire) and transfers captaincy to the identified member at time F.

FIG. 7 is a flow diagram that illustrates an exemplary process that a search head may perform to verify that the search head is qualified to be a captain of the search head cluster based on a set of parameters. As depicted, FIG. 7 begins at block 702, during which a search head in a search head cluster references a set of captaincy qualification parameters for one or more search heads in the search head cluster to determine whether the referencing search head is qualified for the position of search head captain. In one or more embodiments, block 702 may be performed in response to an election—via an election protocol—of the referencing search head to be the current search head captain. Initiation of the election protocol may be performed as described herein, in response to the expiration of a captain-response timer in the referencing search head, for example. Each search head in the search head cluster has a corresponding set of captaincy qualification parameters that may include, inter alia, a configuration replication status and a preferred captain flag. In alternate embodiments, the set of captaincy qualification parameters may also correspond to the computing capability or the computing resources available to the search head relative to other members of the cluster.

As described above, the configuration replication status for a particular search head may consist of a periodically updated status in a shared data structure (such as a lookup table) that corresponds to the last interaction between that search head and the search head captain (which may be the previous search head captain). In one or more embodiments, the data structure may be communicatively coupled to some or all of the search heads of the search head cluster via a network connection, and implemented as, for example, a state machine or on a separate data store accessible to (e.g., read access) each of the search heads. According to further embodiments, write access may be limited only to the current search head captain in the cluster (verified via a flag or other identifier, for example). In alternate embodiments, the shared data structure may be implemented as a module (or portion of a module), that is collectively maintained by the search heads in the search head cluster. For example, the configuration replication status may be implemented as portion of the election module executing in each search head that performs the operations for captaincy election. The configuration replication status may also be propagated as part of the replication of the underlying configurations between search heads, as described above.

The configuration replication status may be updated by the current or previous search head captain based on the last interaction communicated between the search head and any search head having the captain position. For example, if the particular search head is the current captain in the cluster, the configuration replication status may reflect the last interaction between the search head and the most recent captain. Otherwise, if the particular search head is not the current captain but the current captain has changed since the last interaction, the configuration replication status of the search head may also reflect the last interaction between the search head and the previous captain.

In one or more embodiments, the configuration replication status includes a timestamp and a global unique identifier (GUID) of a journal entry (e.g., configuration replication) received from the search head captain and applied in the search head. In further embodiments, the timestamp of the configuration replication status may correspond to the timing of a flag (such as a Boolean flag) received from the search head by the search head captain (either current or previous) that acknowledges the last successful configuration replication. In still further embodiments, the flag may be communicated as part of a communication via a persistent communication channel (such as a heartbeat monitoring thread) maintained between the search head and whichever search head had the position of captain when the last update for that search head was performed.

The preferred captain flag may include a static flag, which may also be a Boolean flag, that was previously established (e.g., by a system administrator) and indicates a preference or lack thereof for the search head for the position of captain. In one or more embodiments, a search head may be preferred for the position of captain based on a locality and/or relative computing capability, as previously described.

In one or more embodiments, the set of captaincy qualification parameters including both the configuration replication status and the preferred captain flag may be stored in a data structure shared between each of the search heads in the cluster.

At block 704, the referencing search head (i.e., the newly elected search head captain) determines its qualification for the position based on its captaincy qualification parameters referenced at block 702. In one or more embodiments, if either the configuration replication status or preferred captain flag indicates that the search head is not qualified for the position, the search head may disqualify itself as captain. The configuration replication status may indicate that the search head is not qualified for the position based on a comparison of the timestamp of the last configuration replication in the current search head captain with the timestamp of the most recent configuration replication in any search head. In further embodiments, if the period of time between the most recent timestamp of the current search head captain and the most recent timestamp of any search head exceeds a pre-determined threshold, the configuration replication status of the current search head captain is changed to indicate the current search head captain is not qualified. If the search head is qualified for the position of captain, the search head remains captain and the process terminates. Otherwise, the process proceeds to block 706.

At block 706, in response to determining the current search head captain is not qualified for the position based on one or more of its captaincy qualification parameters, the current search head captain identifies a second search head in the search head cluster that is more qualified to be the search head captain based on the captaincy qualification parameters referenced in block 702. For example, the configuration replication status of the second search head may indicate that the last configuration replication was performed within the threshold relative to the most recent configuration replication performed on any search head.

At block 708, the role of captain is transferred from the current search head captain to the qualified search head identified as captain. In one or more embodiments, transferal of the position of captain is performed by communicating, from the current search head captain to the search head identified as a qualified captain, a request for the later to initiate an election protocol. The election protocol may be initiated by forcing an immediate expiration of the captain-response timer in the qualified search head. Once the election protocol is initiated by the qualified search head, a request for a vote to confirm the qualified search head as captain is received by the current search head captain (to be unqualified as the captain as determined in block 704) and the current search captain steps down from captaincy and grants its vote towards the qualified search head's claim for captaincy.

FIG. 8 is a flow diagram that illustrates an exemplary process 800 that a search head may perform to manage captaincy qualification parameters for search heads of a search head cluster. As depicted, FIG. 8 begins at block 802 by maintaining, in a current search head captain of the search head cluster in a search environment, a persistent periodic communication channel between the search head captain and each search head of the search head cluster. The persistent periodic communication channel may consist of, for example, a heartbeat monitoring thread.

At block 804, the current search head captain receives a periodic communication from a member search head via the persistent periodic communication channel corresponding to that particular search head, the periodic communication comprising a configuration replication status corresponding to the particular search head. In further embodiments, the periodic communication also includes the preferred-captain flag corresponding to the particular search head.

At block 806, a timestamp is determined corresponding to the configuration replication status based on the timing the periodic communication was received, and a data structure is updated with the configuration replication status and the timestamp of the configuration replication status of the particular search head. In one or more embodiments, the data structure is a shared data structure configured to store a separate configuration replication status for each search head of the search head cluster. In specific embodiments, the data structure may be implemented as, for example, a lookup table (e.g., a key-value lookup table).

2.8. Example Search Screen

FIG. 9A illustrates an example search screen 900 in accordance with the disclosed embodiments. Search screen 900 includes a search bar 902 that accepts user input in the form of a search string. It also includes a time range picker 912 that enables the user to specify a time range for the search. For “historical searches” the user can select a specific time range, or alternatively a relative time range, such as “today,” “yesterday” or “last week.” For “real-time searches,” the user can select the size of a preceding time window to search for real-time events. Search screen 900 also initially displays a “data summary” dialog as is illustrated in FIG. 9B that enables the user to select different sources for the event data, such as by selecting specific hosts and log files.

After the search is executed, the search screen 900 in FIG. 9A can display the results through search results tabs 904, wherein search results tabs 904 includes: an “events tab” that displays various information about events returned by the search; a “statistics tab” that displays statistics about the search results; and a “visualization tab” that displays various visualizations of the search results. The events tab illustrated in FIG. 9A displays a timeline graph 905 that graphically illustrates the number of events that occurred in one-hour intervals over the selected time range. It also displays an events list 908 that enables a user to view the raw data in each of the returned events. It additionally displays a fields sidebar 906 that includes statistics about occurrences of specific fields in the returned events, including “selected fields” that are pre-selected by the user, and “interesting fields” that are automatically selected by the system based on pre-specified criteria.

2.9. Data Models

A data model is a hierarchically structured search-time mapping of semantic knowledge about one or more datasets. It encodes the domain knowledge necessary to build a variety of specialized searches of those datasets. Those searches, in turn, can be used to generate reports.

A data model is composed of one or more “objects” (or “data model objects”) that define or otherwise correspond to a specific set of data.

Objects in data models can be arranged hierarchically in parent/child relationships. Each child object represents a subset of the dataset covered by its parent object. The top-level objects in data models are collectively referred to as “root objects.”

Child objects have inheritance. Data model objects are defined by characteristics that mostly break down into constraints and attributes. Child objects inherit constraints and attributes from their parent objects and have additional constraints and attributes of their own. Child objects provide a way of filtering events from parent objects. Because a child object always provides an additional constraint in addition to the constraints it has inherited from its parent object, the dataset it represents is always a subset of the dataset that its parent represents.

For example, a first data model object may define a broad set of data pertaining to e-mail activity generally, and another data model object may define specific datasets within the broad dataset, such as a subset of the e-mail data pertaining specifically to e-mails sent. Examples of data models can include electronic mail, authentication, databases, intrusion detection, malware, application state, alerts, compute inventory, network sessions, network traffic, performance, audits, updates, vulnerabilities, etc. Data models and their objects can be designed by knowledge managers in an organization, and they can enable downstream users to quickly focus on a specific set of data. For example, a user can simply select an “e-mail activity” data model object to access a dataset relating to e-mails generally (e.g., sent or received), or select an “e-mails sent” data model object (or data sub-model object) to access a dataset relating to e-mails sent.

A data model object may be defined by (1) a set of search constraints, and (2) a set of fields. Thus, a data model object can be used to quickly search data to identify a set of events and to identify a set of fields to be associated with the set of events. For example, an “e-mails sent” data model object may specify a search for events relating to e-mails that have been sent, and specify a set of fields that are associated with the events. Thus, a user can retrieve and use the “e-mails sent” data model object to quickly search source data for events relating to sent e-mails, and may be provided with a listing of the set of fields relevant to the events in a user interface screen.

A child of the parent data model may be defined by a search (typically a narrower search) that produces a subset of the events that would be produced by the parent data model's search. The child's set of fields can include a subset of the set of fields of the parent data model and/or additional fields. Data model objects that reference the subsets can be arranged in a hierarchical manner, so that child subsets of events are proper subsets of their parents. A user iteratively applies a model development tool (not shown in Fig.) to prepare a query that defines a subset of events and assigns an object name to that subset. A child subset is created by further limiting a query that generated a parent subset. A late-binding schema of field extraction rules is associated with each object or subset in the data model.

Data definitions in associated schemas can be taken from the common information model (CIM) or can be devised for a particular schema and optionally added to the CIM. Child objects inherit fields from parents and can include fields not present in parents. A model developer can select fewer extraction rules than are available for the sources returned by the query that defines events belonging to a model. Selecting a limited set of extraction rules can be a tool for simplifying and focusing the data model, while allowing a user flexibility to explore the data subset. Development of a data model is further explained in U.S. Pat. Nos. 8,788,525 and 8,788,526, both entitled “DATA MODEL FOR MACHINE DATA FOR SEMANTIC SEARCH”, both issued on 22 Jul. 2014, U.S. Pat. No. 8,983,994, entitled “GENERATION OF A DATA MODEL FOR SEARCHING MACHINE DATA”, issued on 17 Mar. 2015, U.S. patent application Ser. No. 14/611,232, entitled “GENERATION OF A DATA MODEL APPLIED TO QUERIES”, filed on 31 Jan. 2015, and U.S. patent application Ser. No. 14/815,884, entitled “GENERATION OF A DATA MODEL APPLIED TO OBJECT QUERIES”, filed on 31 Jul. 2015, each of which is hereby incorporated by reference in its entirety for all purposes. See, also, Knowledge Manager Manual, Build a Data Model, Splunk Enterprise 6.1.3 pp. 150-204 (Aug. 25, 2014).

A data model can also include reports. One or more report formats can be associated with a particular data model and be made available to run against the data model. A user can use child objects to design reports with object datasets that already have extraneous data pre-filtered out. In an embodiment, the data intake and query system 108 provides the user with the ability to produce reports (e.g., a table, chart, visualization, etc.) without having to enter SPL, SQL, or other query language terms into a search screen. Data models are used as the basis for the search feature.

Data models may be selected in a report generation interface. The report generator supports drag-and-drop organization of fields to be summarized in a report. When a model is selected, the fields with available extraction rules are made available for use in the report. The user may refine and/or filter search results to produce more precise reports. The user may select some fields for organizing the report and select other fields for providing detail according to the report organization. For example, “region” and “salesperson” are fields used for organizing the report and sales data can be summarized (subtotaled and totaled) within this organization. The report generator allows the user to specify one or more fields within events and apply statistical analysis on values extracted from the specified one or more fields. The report generator may aggregate search results across sets of events and generate statistics based on aggregated search results. Building reports using the report generation interface is further explained in U.S. patent application Ser. No. 14/503,335, entitled “GENERATING REPORTS FROM UNSTRUCTURED DATA”, filed on 30 Sep. 2014, and which is hereby incorporated by reference in its entirety for all purposes, and in Pivot Manual, Splunk Enterprise 6.1.3 (Aug. 4, 2014). Data visualizations also can be generated in a variety of formats, by reference to the data model. Reports, data visualizations, and data model objects can be saved and associated with the data model for future use. The data model object may be used to perform searches of other data.

FIGS. 15, 16, and 10A-10D illustrate a series of user interface screens where a user may select report generation options using data models. The report generation process may be driven by a predefined data model object, such as a data model object defined and/or saved via a reporting application or a data model object obtained from another source. A user can load a saved data model object using a report editor. For example, the initial search query and fields used to drive the report editor may be obtained from a data model object. The data model object that is used to drive a report generation process may define a search and a set of fields. Upon loading of the data model object, the report generation process may enable a user to use the fields (e.g., the fields defined by the data model object) to define criteria for a report (e.g., filters, split rows/columns, aggregates, etc.) and the search may be used to identify events (e.g., to identify events responsive to the search) used to generate the report. That is, for example, if a data model object is selected to drive a report editor, the graphical user interface of the report editor may enable a user to define reporting criteria for the report using the fields associated with the selected data model object, and the events used to generate the report may be constrained to the events that match, or otherwise satisfy, the search constraints of the selected data model object.

The selection of a data model object for use in driving a report generation may be facilitated by a data model object selection interface. FIG. 15 illustrates an example interactive data model selection graphical user interface 1500 of a report editor that displays a listing of available data models 1501. The user may select one of the data models 1502.

FIG. 16 illustrates an example data model object selection graphical user interface 1600 that displays available data objects 1601 for the selected data object model 1502. The user may select one of the displayed data model objects 1602 for use in driving the report generation process.

Once a data model object is selected by the user, a user interface screen 1000 shown in FIG. 10A may display an interactive listing of automatic field identification options 1001 based on the selected data model object. For example, a user may select one of the three illustrated options (e.g., the “All Fields” option 1002, the “Selected Fields” option 1003, or the “Coverage” option (e.g., fields with at least a specified % of coverage) 1004). If the user selects the “All Fields” option 1002, all of the fields identified from the events that were returned in response to an initial search query may be selected. That is, for example, all of the fields of the identified data model object fields may be selected. If the user selects the “Selected Fields” option 1003, only the fields from the fields of the identified data model object fields that are selected by the user may be used. If the user selects the “Coverage” option 1004, only the fields of the identified data model object fields meeting a specified coverage criteria may be selected. A percent coverage may refer to the percentage of events returned by the initial search query that a given field appears in. Thus, for example, if an object dataset includes 10,000 events returned in response to an initial search query, and the “avg_age” field appears in 854 of those 10,000 events, then the “avg_age” field would have a coverage of 8.54% for that object dataset. If, for example, the user selects the “Coverage” option and specifies a coverage value of 2%, only fields having a coverage value equal to or greater than 2% may be selected. The number of fields corresponding to each selectable option may be displayed in association with each option. For example, “97” displayed next to the “All Fields” option 1002 indicates that 97 fields will be selected if the “All Fields” option is selected. The “3” displayed next to the “Selected Fields” option 1003 indicates that 3 of the 97 fields will be selected if the “Selected Fields” option is selected. The “49” displayed next to the “Coverage” option 1004 indicates that 49 of the 97 fields (e.g., the 49 fields having a coverage of 2% or greater) will be selected if the “Coverage” option is selected. The number of fields corresponding to the “Coverage” option may be dynamically updated based on the specified percent of coverage.

FIG. 10B illustrates an example graphical user interface screen (also called the pivot interface) 1005 displaying the reporting application's “Report Editor” page. The screen may display interactive elements for defining various elements of a report. For example, the page includes a “Filters” element 1006, a “Split Rows” element 1007, a “Split Columns” element 1008, and a “Column Values” element 1009. The page may include a list of search results 1011. In this example, the Split Rows element 1007 is expanded, revealing a listing of fields 1010 that can be used to define additional criteria (e.g., reporting criteria). The listing of fields 1010 may correspond to the selected fields (attributes). That is, the listing of fields 1010 may list only the fields previously selected, either automatically and/or manually by a user. FIG. 10C illustrates a formatting dialogue 1012 that may be displayed upon selecting a field from the listing of fields 1010. The dialogue can be used to format the display of the results of the selection (e.g., label the column to be displayed as “component”).

FIG. 10D illustrates an example graphical user interface screen 1005 including a table of results 1013 based on the selected criteria including splitting the rows by the “component” field. A column 1014 having an associated count for each component listed in the table may be displayed that indicates an aggregate count of the number of times that the particular field-value pair (e.g., the value in a row) occurs in the set of events responsive to the initial search query.

FIG. 17 illustrates an example graphical user interface screen 1700 that allows the user to filter search results and to perform statistical analysis on values extracted from specific fields in the set of events. In this example, the top ten product names ranked by price are selected as a filter 1701 that causes the display of the ten most popular products sorted by price. Each row is displayed by product name and price 1702. This results in each product displayed in a column labeled “product name” along with an associated price in a column labeled “price” 1706. Statistical analysis of other fields in the events associated with the ten most popular products have been specified as column values 1703. A count of the number of successful purchases for each product is displayed in column 1704. This statistics may be produced by filtering the search results by the product name, finding all occurrences of a successful purchase in a field within the events and generating a total of the number of occurrences. A sum of the total sales is displayed in column 1705, which is a result of the multiplication of the price and the number of successful purchases for each product.

The reporting application allows the user to create graphical visualizations of the statistics generated for a report. For example, FIG. 18 illustrates an example graphical user interface 1800 that displays a set of components and associated statistics 1801. The reporting application allows the user to select a visualization of the statistics in a graph (e.g., bar chart, scatter plot, area chart, line chart, pie chart, radial gauge, marker gauge, filler gauge, etc.). FIG. 19 illustrates an example of a bar chart visualization 1900 of an aspect of the statistical data 1801. FIG. 20 illustrates a scatter plot visualization 2000 of an aspect of the statistical data 1801.

2.10. Acceleration Technique

The above-described system provides significant flexibility by enabling a user to analyze massive quantities of minimally processed data “on the fly” at search time instead of storing pre-specified portions of the data in a database at ingestion time. This flexibility enables a user to see valuable insights, correlate data, and perform subsequent queries to examine interesting aspects of the data that may not have been apparent at ingestion time.

However, performing extraction and analysis operations at search time can involve a large amount of data and require a large number of computational operations, which can cause delays in processing the queries. Advantageously, SPLUNK® ENTERPRISE system employs a number of unique acceleration techniques that have been developed to speed up analysis operations performed at search time. These techniques include: (1) performing search operations in parallel across multiple indexers; (2) using a keyword index; (3) using a high performance analytics store; and (4) accelerating the process of generating reports. These novel techniques are described in more detail below.

2.10.1. Aggregation Technique

To facilitate faster query processing, a query can be structured such that multiple indexers perform the query in parallel, while aggregation of search results from the multiple indexers is performed locally at the search head. For example, FIG. 11 illustrates how a search query 1102 received from a client at a search head 210 can split into two phases, including: (1) subtasks 1104 (e.g., data retrieval or simple filtering) that may be performed in parallel by indexers 206 for execution, and (2) a search results aggregation operation 506 to be executed by the search head when the results are ultimately collected from the indexers.

During operation, upon receiving search query 1102, a search head 210 determines that a portion of the operations involved with the search query may be performed locally by the search head. The search head modifies search query 1102 by substituting “stats” (create aggregate statistics over results sets received from the indexers at the search head) with “prestats” (create statistics by the indexer from local results set) to produce search query 1104, and then distributes search query 1104 to distributed indexers, which are also referred to as “search peers.” Note that search queries may generally specify search criteria or operations to be performed on events that meet the search criteria. Search queries may also specify field names, as well as search criteria for the values in the fields or operations to be performed on the values in the fields. Moreover, the search head may distribute the full search query to the search peers as illustrated in FIG. 4, or may alternatively distribute a modified version (e.g., a more restricted version) of the search query to the search peers. In this example, the indexers are responsible for producing the results and sending them to the search head. After the indexers return the results to the search head, the search head aggregates the received results 506 to form a single search result set. By executing the query in this manner, the system effectively distributes the computational operations across the indexers while minimizing data transfers.

2.10.2. Keyword Index

As described above with reference to the flow charts in (inter alia) FIG. 3 and FIG. 4, data intake and query system 108 can construct and maintain one or more keyword indices to quickly identify events containing specific keywords. This technique can greatly speed up the processing of queries involving specific keywords. As mentioned above, to build a keyword index, an indexer first identifies a set of keywords. Then, the indexer includes the identified keywords in an index, which associates each stored keyword with references to events containing that keyword, or to locations within events where that keyword is located. When an indexer subsequently receives a keyword-based query, the indexer can access the keyword index to quickly identify events containing the keyword.

2.10.3. High Performance Analytics Store

To speed up certain types of queries, some embodiments of system 108 create a high performance analytics store, which is referred to as a “summarization table,” that contains entries for specific field-value pairs. Each of these entries keeps track of instances of a specific value in a specific field in the event data and includes references to events containing the specific value in the specific field. For example, an example entry in a summarization table can keep track of occurrences of the value “94107” in a “ZIP code” field of a set of events and the entry includes references to all of the events that contain the value “94107” in the ZIP code field. This optimization technique enables the system to quickly process queries that seek to determine how many events have a particular value for a particular field. To this end, the system can examine the entry in the summarization table to count instances of the specific value in the field without having to go through the individual events or perform data extractions at search time. Also, if the system needs to process all events that have a specific field-value combination, the system can use the references in the summarization table entry to directly access the events to extract further information without having to search all of the events to find the specific field-value combination at search time.

In some embodiments, the system maintains a separate summarization table for each of the above-described time-specific buckets that stores events for a specific time range. A bucket-specific summarization table includes entries for specific field-value combinations that occur in events in the specific bucket. Alternatively, the system can maintain a separate summarization table for each indexer. The indexer-specific summarization table includes entries for the events in a data store that are managed by the specific indexer. Indexer-specific summarization tables may also be bucket-specific.

The summarization table can be populated by running a periodic query that scans a set of events to find instances of a specific field-value combination, or alternatively instances of all field-value combinations for a specific field. A periodic query can be initiated by a user, or can be scheduled to occur automatically at specific time intervals. A periodic query can also be automatically launched in response to a query that asks for a specific field-value combination.

In some cases, when the summarization tables may not cover all of the events that are relevant to a query, the system can use the summarization tables to obtain partial results for the events that are covered by summarization tables, but may also have to search through other events that are not covered by the summarization tables to produce additional results. These additional results can then be combined with the partial results to produce a final set of results for the query. The summarization table and associated techniques are described in more detail in U.S. Pat. No. 8,682,925, entitled “DISTRIBUTED HIGH PERFORMANCE ANALYTICS STORE”, issued on 25 Mar. 2014, U.S. patent application Ser. No. 14/170,159, entitled “SUPPLEMENTING A HIGH PERFORMANCE ANALYTICS STORE WITH EVALUATION OF INDIVIDUAL EVENTS TO RESPOND TO AN EVENT QUERY”, filed on 31 Jan. 2014, and U.S. patent application Ser. No. 14/815,973, entitled “STORAGE MEDIUM AND CONTROL DEVICE”, filed on 21 Feb. 2014, each of which is hereby incorporated by reference in its entirety.

2.10.4. Accelerating Report Generation

In some embodiments, a data server system such as the SPLUNK® ENTERPRISE system can accelerate the process of periodically generating updated reports based on query results. To accelerate this process, a summarization engine automatically examines the query to determine whether generation of updated reports can be accelerated by creating intermediate summaries. If reports can be accelerated, the summarization engine periodically generates a summary covering data obtained during a latest non-overlapping time period. For example, where the query seeks events meeting a specified criteria, a summary for the time period includes only events within the time period that meet the specified criteria. Similarly, if the query seeks statistics calculated from the events, such as the number of events that match the specified criteria, then the summary for the time period includes the number of events in the period that match the specified criteria.

In addition to the creation of the summaries, the summarization engine schedules the periodic updating of the report associated with the query. During each scheduled report update, the query engine determines whether intermediate summaries have been generated covering portions of the time period covered by the report update. If so, then the report is generated based on the information contained in the summaries. Also, if additional event data has been received and has not yet been summarized, and is required to generate the complete report, the query can be run on this additional event data. Then, the results returned by this query on the additional event data, along with the partial results obtained from the intermediate summaries, can be combined to generate the updated report. This process is repeated each time the report is updated. Alternatively, if the system stores events in buckets covering specific time ranges, then the summaries can be generated on a bucket-by-bucket basis. Note that producing intermediate summaries can save the work involved in re-running the query for previous time periods, so advantageously only the newer event data needs to be processed while generating an updated report. These report acceleration techniques are described in more detail in U.S. Pat. No. 8,589,403, entitled “COMPRESSED JOURNALING IN EVENT TRACKING FILES FOR METADATA RECOVERY AND REPLICATION”, issued on 19 Nov. 2013, U.S. Pat. No. 8,412,696, entitled “REAL TIME SEARCHING AND REPORTING”, issued on 2 Apr. 2011, and U.S. Pat. Nos. 8,589,375 and 8,589,432, both also entitled “REAL TIME SEARCHING AND REPORTING”, both issued on 19 Nov. 2013, each of which is hereby incorporated by reference in its entirety.

2.11. Security Features

The SPLUNK® ENTERPRISE platform provides various schemas, dashboards and visualizations that simplify developers' task to create applications with additional capabilities. One such application is the SPLUNK® APP FOR ENTERPRISE SECURITY, which performs monitoring and alerting operations and includes analytics to facilitate identifying both known and unknown security threats based on large volumes of data stored by the SPLUNK® ENTERPRISE system. SPLUNK® APP FOR ENTERPRISE SECURITY provides the security practitioner with visibility into security-relevant threats found in the enterprise infrastructure by capturing, monitoring, and reporting on data from enterprise security devices, systems, and applications. Through the use of SPLUNK® ENTERPRISE searching and reporting capabilities, SPLUNK® APP FOR ENTERPRISE SECURITY provides a top-down and bottom-up view of an organization's security posture.

The SPLUNK® APP FOR ENTERPRISE SECURITY leverages SPLUNK® ENTERPRISE search-time normalization techniques, saved searches, and correlation searches to provide visibility into security-relevant threats and activity and generate notable events for tracking. The App enables the security practitioner to investigate and explore the data to find new or unknown threats that do not follow signature-based patterns.

Conventional Security Information and Event Management (SIEM) systems that lack the infrastructure to effectively store and analyze large volumes of security-related data. Traditional SIEM systems typically use fixed schemas to extract data from pre-defined security-related fields at data ingestion time and storing the extracted data in a relational database. This traditional data extraction process (and associated reduction in data size) that occurs at data ingestion time inevitably hampers future incident investigations that may need original data to determine the root cause of a security issue, or to detect the onset of an impending security threat.

In contrast, the SPLUNK® APP FOR ENTERPRISE SECURITY system stores large volumes of minimally processed security-related data at ingestion time for later retrieval and analysis at search time when a live security threat is being investigated. To facilitate this data retrieval process, the SPLUNK® APP FOR ENTERPRISE SECURITY provides pre-specified schemas for extracting relevant values from the different types of security-related event data and enables a user to define such schemas.

The SPLUNK® APP FOR ENTERPRISE SECURITY can process many types of security-related information. In general, this security-related information can include any information that can be used to identify security threats. For example, the security-related information can include network-related information, such as IP addresses, domain names, asset identifiers, network traffic volume, uniform resource locator strings, and source addresses. The process of detecting security threats for network-related information is further described in U.S. Pat. No. 8,826,434, entitled “SECURITY THREAT DETECTION BASED ON INDICATIONS IN BIG DATA OF ACCESS TO NEWLY REGISTERED DOMAINS”, issued on 2 Sep. 2014, U.S. patent application Ser. No. 13/956,252, entitled “INVESTIGATIVE AND DYNAMIC DETECTION OF POTENTIAL SECURITY-THREAT INDICATORS FROM EVENTS IN BIG DATA”, filed on 31 Jul. 2013, U.S. patent application Ser. No. 14/445,018, entitled “GRAPHIC DISPLAY OF SECURITY THREATS BASED ON INDICATIONS OF ACCESS TO NEWLY REGISTERED DOMAINS”, filed on 28 Jul. 2014, U.S. patent application Ser. No. 14/445,023, entitled “SECURITY THREAT DETECTION OF NEWLY REGISTERED DOMAINS”, filed on 28 Jul. 2014, U.S. patent application Ser. No. 14/815,971, entitled “SECURITY THREAT DETECTION USING DOMAIN NAME ACCESSES”, filed on 1 Aug. 2015, and U.S. patent application Ser. No. 14/815,972, entitled “SECURITY THREAT DETECTION USING DOMAIN NAME REGISTRATIONS”, filed on 1 Aug. 2015, each of which is hereby incorporated by reference in its entirety for all purposes. Security-related information can also include malware infection data and system configuration information, as well as access control information, such as login/logout information and access failure notifications. The security-related information can originate from various sources within a data center, such as hosts, virtual machines, storage devices and sensors. The security-related information can also originate from various sources in a network, such as routers, switches, email servers, proxy servers, gateways, firewalls and intrusion-detection systems.

During operation, the SPLUNK® APP FOR ENTERPRISE SECURITY facilitates detecting “notable events” that are likely to indicate a security threat. These notable events can be detected in a number of ways: (1) a user can notice a correlation in the data and can manually identify a corresponding group of one or more events as “notable;” or (2) a user can define a “correlation search” specifying criteria for a notable event, and every time one or more events satisfy the criteria, the application can indicate that the one or more events are notable. A user can alternatively select a pre-defined correlation search provided by the application. Note that correlation searches can be run continuously or at regular intervals (e.g., every hour) to search for notable events. Upon detection, notable events can be stored in a dedicated “notable events index,” which can be subsequently accessed to generate various visualizations containing security-related information. Also, alerts can be generated to notify system operators when important notable events are discovered.

The SPLUNK® APP FOR ENTERPRISE SECURITY provides various visualizations to aid in discovering security threats, such as a “key indicators view” that enables a user to view security metrics, such as counts of different types of notable events. For example, FIG. 12A illustrates an example key indicators view 1200 that comprises a dashboard, which can display a value 1201, for various security-related metrics, such as malware infections 1202. It can also display a change in a metric value 1203, which indicates that the number of malware infections increased by 63 during the preceding interval. Key indicators view 1200 additionally displays a histogram panel 1204 that displays a histogram of notable events organized by urgency values, and a histogram of notable events organized by time intervals. This key indicators view is described in further detail in pending U.S. patent application Ser. No. 13/956,338, entitled “KEY INDICATORS VIEW”, filed on 31 Jul. 2013, and which is hereby incorporated by reference in its entirety for all purposes.

These visualizations can also include an “incident review dashboard” that enables a user to view and act on “notable events.” These notable events can include: (1) a single event of high importance, such as any activity from a known web attacker; or (2) multiple events that collectively warrant review, such as a large number of authentication failures on a host followed by a successful authentication. For example, FIG. 12B illustrates an example incident review dashboard 1210 that includes a set of incident attribute fields 1211 that, for example, enables a user to specify a time range field 1212 for the displayed events. It also includes a timeline 1213 that graphically illustrates the number of incidents that occurred in time intervals over the selected time range. It additionally displays an events list 1214 that enables a user to view a list of all of the notable events that match the criteria in the incident attributes fields 1211. To facilitate identifying patterns among the notable events, each notable event can be associated with an urgency value (e.g., low, medium, high, critical), which is indicated in the incident review dashboard. The urgency value for a detected event can be determined based on the severity of the event and the priority of the system component associated with the event.

2.12. Data Center Monitoring

As mentioned above, the SPLUNK® ENTERPRISE platform provides various features that simplify the developers' task to create various applications. One such application is SPLUNK® APP FOR VMWARE® that provides operational visibility into granular performance metrics, logs, tasks and events, and topology from hosts, virtual machines and virtual centers. It empowers administrators with an accurate real-time picture of the health of the environment, proactively identifying performance and capacity bottlenecks.

Conventional data-center-monitoring systems lack the infrastructure to effectively store and analyze large volumes of machine-generated data, such as performance information and log data obtained from the data center. In conventional data-center-monitoring systems, machine-generated data is typically pre-processed prior to being stored, for example, by extracting pre-specified data items and storing them in a database to facilitate subsequent retrieval and analysis at search time. However, the rest of the data is not saved and discarded during pre-processing.

In contrast, the SPLUNK® APP FOR VMWARE® stores large volumes of minimally processed machine data, such as performance information and log data, at ingestion time for later retrieval and analysis at search time when a live performance issue is being investigated. In addition to data obtained from various log files, this performance-related information can include values for performance metrics obtained through an application programming interface (API) provided as part of the vSphere Hypervisor™ system distributed by VMware, Inc. of Palo Alto, Calif. For example, these performance metrics can include: (1) CPU-related performance metrics; (2) disk-related performance metrics; (3) memory-related performance metrics; (4) network-related performance metrics; (5) energy-usage statistics; (6) data-traffic-related performance metrics; (7) overall system availability performance metrics; (8) cluster-related performance metrics; and (9) virtual machine performance statistics. Such performance metrics are described in U.S. patent application Ser. No. 14/167,316, entitled “CORRELATION FOR USER-SELECTED TIME RANGES OF VALUES FOR PERFORMANCE METRICS OF COMPONENTS IN AN INFORMATION-TECHNOLOGY ENVIRONMENT WITH LOG DATA FROM THAT INFORMATION-TECHNOLOGY ENVIRONMENT”, filed on 29 Jan. 2014, and which is hereby incorporated by reference in its entirety for all purposes.

To facilitate retrieving information of interest from performance data and log files, the SPLUNK® APP FOR VMWARE® provides pre-specified schemas for extracting relevant values from different types of performance-related event data, and also enables a user to define such schemas.

The SPLUNK® APP FOR VMWARE® additionally provides various visualizations to facilitate detecting and diagnosing the root cause of performance problems. For example, one such visualization is a “proactive monitoring tree” that enables a user to easily view and understand relationships among various factors that affect the performance of a hierarchically structured computing system. This proactive monitoring tree enables a user to easily navigate the hierarchy by selectively expanding nodes representing various entities (e.g., virtual centers or computing clusters) to view performance information for lower-level nodes associated with lower-level entities (e.g., virtual machines or host systems). Example node-expansion operations are illustrated in FIG. 12C, wherein nodes 1233 and 1234 are selectively expanded. Note that nodes 1231-1239 can be displayed using different patterns or colors to represent different performance states, such as a critical state, a warning state, a normal state or an unknown/offline state. The ease of navigation provided by selective expansion in combination with the associated performance-state information enables a user to quickly diagnose the root cause of a performance problem. The proactive monitoring tree is described in further detail in U.S. patent application Ser. No. 14/253,490, entitled “PROACTIVE MONITORING TREE WITH SEVERITY STATE SORTING”, filed on 15 Apr. 2014, and U.S. patent application Ser. No. 14/812,948, also entitled “PROACTIVE MONITORING TREE WITH SEVERITY STATE SORTING”, filed on 29 Jul. 2015, each of which is hereby incorporated by reference in its entirety for all purposes.

The SPLUNK® APP FOR VMWARE® also provides a user interface that enables a user to select a specific time range and then view heterogeneous data comprising events, log data, and associated performance metrics for the selected time range. For example, the screen illustrated in FIG. 12D displays a listing of recent “tasks and events” and a listing of recent “log entries” for a selected time range above a performance-metric graph for “average CPU core utilization” for the selected time range. Note that a user is able to operate pull-down menus 1242 to selectively display different performance metric graphs for the selected time range. This enables the user to correlate trends in the performance-metric graph with corresponding event and log data to quickly determine the root cause of a performance problem. This user interface is described in more detail in U.S. patent application Ser. No. 14/167,316, entitled “CORRELATION FOR USER-SELECTED TIME RANGES OF VALUES FOR PERFORMANCE METRICS OF COMPONENTS IN AN INFORMATION-TECHNOLOGY ENVIRONMENT WITH LOG DATA FROM THAT INFORMATION-TECHNOLOGY ENVIRONMENT”, filed on 29 Jan. 2014, and which is hereby incorporated by reference in its entirety for all purposes.

2.13. Cloud-Based System Overview

The example data intake and query system 108 described in reference to FIG. 2 comprises several system components, including one or more forwarders, indexers, and search heads. In some environments, a user of a data intake and query system 108 may install and configure, on computing devices owned and operated by the user, one or more software applications that implement some or all of these system components. For example, a user may install a software application on server computers owned by the user and configure each server to operate as one or more of a forwarder, an indexer, a search head, etc. This arrangement generally may be referred to as an “on-premises” solution. That is, the system 108 is installed and operates on computing devices directly controlled by the user of the system. Some users may prefer an on-premises solution because it may provide a greater level of control over the configuration of certain aspects of the system (e.g., security, privacy, standards, controls, etc.). However, other users may instead prefer an arrangement in which the user is not directly responsible for providing and managing the computing devices upon which various components of system 108 operate.

In one embodiment, to provide an alternative to an entirely on-premises environment for system 108, one or more of the components of a data intake and query system instead may be provided as a cloud-based service. In this context, a cloud-based service refers to a service hosted by one more computing resources that are accessible to end users over a network, for example, by using a web browser or other application on a client device to interface with the remote computing resources. For example, a service provider may provide a cloud-based data intake and query system by managing computing resources configured to implement various aspects of the system (e.g., forwarders, indexers, search heads, etc.) and by providing access to the system to end users via a network. Typically, a user may pay a subscription or other fee to use such a service. Each subscribing user of the cloud-based service may be provided with an account that enables the user to configure a customized cloud-based system based on the user's preferences.

FIG. 13 illustrates a block diagram of an example cloud-based data intake and query system. Similar to the system of FIG. 2, the networked computer system 1300 includes input data sources 202 and forwarders 204. These input data sources and forwarders may be in a subscriber's private computing environment. Alternatively, they might be directly managed by the service provider as part of the cloud service. In the example system 1300, one or more forwarders 204 and client devices 1302 are coupled to a cloud-based data intake and query system 1306 via one or more networks 1304. Network 1304 broadly represents one or more LANs, WANs, cellular networks, intranetworks, internetworks, etc., using any of wired, wireless, terrestrial microwave, satellite links, etc., and may include the public Internet, and is used by client devices 1302 and forwarders 204 to access the system 1306. Similar to the system of 108, each of the forwarders 204 may be configured to receive data from an input source and to forward the data to other components of the system 1306 for further processing.

In an embodiment, a cloud-based data intake and query system 1306 may comprise a plurality of system instances 1308. In general, each system instance 1308 may include one or more computing resources managed by a provider of the cloud-based system 1306 made available to a particular subscriber. The computing resources comprising a system instance 1308 may, for example, include one or more servers or other devices configured to implement one or more forwarders, indexers, search heads, and other components of a data intake and query system, similar to system 108. As indicated above, a subscriber may use a web browser or other application of a client device 1302 to access a web portal or other interface that enables the subscriber to configure an instance 1308.

Providing a data intake and query system as described in reference to system 108 as a cloud-based service presents a number of challenges. Each of the components of a system 108 (e.g., forwarders, indexers and search heads) may at times refer to various configuration files stored locally at each component. These configuration files typically may involve some level of user configuration to accommodate particular types of data a user desires to analyze and to account for other user preferences. However, in a cloud-based service context, users typically may not have direct access to the underlying computing resources implementing the various system components (e.g., the computing resources comprising each system instance 1308) and may desire to make such configurations indirectly, for example, using one or more web-based interfaces. Thus, the techniques and systems described herein for providing user interfaces that enable a user to configure source type definitions are applicable to both on-premises and cloud-based service contexts, or some combination thereof (e.g., a hybrid system where both an on-premises environment such as SPLUNK® ENTERPRISE and a cloud-based environment such as SPLUNK CLOUD™ are centrally visible).

2.14. Searching Externally Archived Data

FIG. 14 shows a block diagram of an example of a data intake and query system 108 that provides transparent search facilities for data systems that are external to the data intake and query system. Such facilities are available in the HUNK® system provided by Splunk Inc. of San Francisco, Calif. HUNK® represents an analytics platform that enables business and IT teams to rapidly explore, analyze, and visualize data in Hadoop and NoSQL data stores.

The search head 210 of the data intake and query system receives search requests from one or more client devices 1404 over network connections 1420. As discussed above, the data intake and query system 108 may reside in an enterprise location, in the cloud, etc. FIG. 14 illustrates that multiple client devices 1404 a, 1404 b, . . . , 1404 n may communicate with the data intake and query system 108. The client devices 1404 may communicate with the data intake and query system using a variety of connections. For example, one client device in FIG. 14 is illustrated as communicating over an Internet (Web) protocol, another client device is illustrated as communicating via a command line interface, and another client device is illustrated as communicating via a system developer kit (SDK).

The search head 210 analyzes the received search request to identify request parameters. If a search request received from one of the client devices 1404 references an index maintained by the data intake and query system, then the search head 210 connects to one or more indexers 206 of the data intake and query system for the index referenced in the request parameters. That is, if the request parameters of the search request reference an index, then the search head accesses the data in the index via the indexer. The data intake and query system 108 may include one or more indexers 206, depending on system access resources and requirements. As described further below, the indexers 206 retrieve data from their respective local data stores 208 as specified in the search request. The indexers and their respective data stores can comprise one or more storage devices and typically reside on the same system, though they may be connected via a local network connection.

If the request parameters of the received search request reference an external data collection, which is not accessible to the indexers 206 or under the management of the data intake and query system, then the search head 210 can access the external data collection through an External Result Provider (ERP) process 1410. An external data collection may be referred to as a “virtual index” (plural, “virtual indices”). An ERP process provides an interface through which the search head 210 may access virtual indices.

Thus, a search reference to an index of the system relates to a locally stored and managed data collection. In contrast, a search reference to a virtual index relates to an externally stored and managed data collection, which the search head may access through one or more ERP processes 1410, 1412. FIG. 14 shows two ERP processes 1410, 1412 that connect to respective remote (external) virtual indices, which are indicated as a Hadoop or another system 1414 (e.g., Amazon S3, Amazon EMR, other Hadoop Compatible File Systems (HCFS), etc.) and a relational database management system (RDBMS) 1416. Other virtual indices may include other file organizations and protocols, such as Structured Query Language (SQL) and the like. The ellipses between the ERP processes 1410, 1412 indicate optional additional ERP processes of the data intake and query system 108. An ERP process may be a computer process that is initiated or spawned by the search head 210 and is executed by the search data intake and query system 108. Alternatively or additionally, an ERP process may be a process spawned by the search head 210 on the same or different host system as the search head 210 resides.

The search head 210 may spawn a single ERP process in response to multiple virtual indices referenced in a search request, or the search head may spawn different ERP processes for different virtual indices. Generally, virtual indices that share common data configurations or protocols may share ERP processes. For example, all search query references to a Hadoop file system may be processed by the same ERP process, if the ERP process is suitably configured. Likewise, all search query references to an SQL database may be processed by the same ERP process. In addition, the search head may provide a common ERP process for common external data source types (e.g., a common vendor may utilize a common ERP process, even if the vendor includes different data storage system types, such as Hadoop and SQL). Common indexing schemes also may be handled by common ERP processes, such as flat text files or Weblog files.

The search head 210 determines the number of ERP processes to be initiated via the use of configuration parameters that are included in a search request message. Generally, there is a one-to-many relationship between an external results provider “family” and ERP processes. There is also a one-to-many relationship between an ERP process and corresponding virtual indices that are referred to in a search request. For example, using RDBMS, assume two independent instances of such a system by one vendor, such as one RDBMS for production and another RDBMS used for development. In such a situation, it is likely preferable (but optional) to use two ERP processes to maintain the independent operation as between production and development data. Both of the ERPs, however, will belong to the same family, because the two RDBMS system types are from the same vendor.

The ERP processes 1410, 1412 receive a search request from the search head 210. The search head may optimize the received search request for execution at the respective external virtual index. Alternatively, the ERP process may receive a search request as a result of analysis performed by the search head or by a different system process. The ERP processes 1410, 1412 can communicate with the search head 210 via conventional input/output routines (e.g., standard in/standard out, etc.). In this way, the ERP process receives the search request from a client device such that the search request may be efficiently executed at the corresponding external virtual index.

The ERP processes 1410, 1412 may be implemented as a process of the data intake and query system. Each ERP process may be provided by the data intake and query system, or may be provided by process or application providers who are independent of the data intake and query system. Each respective ERP process may include an interface application installed at a computer of the external result provider that ensures proper communication between the search support system and the external result provider. The ERP processes 1410, 1412 generate appropriate search requests in the protocol and syntax of the respective virtual indices 1414, 1416, each of which corresponds to the search request received by the search head 210. Upon receiving search results from their corresponding virtual indices, the respective ERP process passes the result to the search head 210, which may return or display the results or a processed set of results based on the returned results to the respective client device.

Client devices 1404 may communicate with the data intake and query system 108 through a network interface 1420, e.g., one or more LANs, WANs, cellular networks, intranetworks, and/or internetworks using any of wired, wireless, terrestrial microwave, satellite links, etc., and may include the public Internet.

The analytics platform utilizing the External Result Provider process described in more detail in U.S. Pat. No. 8,738,629, entitled “EXTERNAL RESULT PROVIDED PROCESS FOR RETRIEVING DATA STORED USING A DIFFERENT CONFIGURATION OR PROTOCOL”, issued on 27 May 2014, U.S. Pat. No. 8,738,587, entitled “PROCESSING A SYSTEM SEARCH REQUEST BY RETRIEVING RESULTS FROM BOTH A NATIVE INDEX AND A VIRTUAL INDEX”, issued on 25 Jul. 2013, U.S. patent application Ser. No. 14/266,832, entitled “PROCESSING A SYSTEM SEARCH REQUEST ACROSS DISPARATE DATA COLLECTION SYSTEMS”, filed on 1 May 2014, and U.S. patent application Ser. No. 14/449,144, entitled “PROCESSING A SYSTEM SEARCH REQUEST INCLUDING EXTERNAL DATA SOURCES”, filed on 31 Jul. 2014, each of which is hereby incorporated by reference in its entirety for all purposes.

2.14.1. ERP Process Features

The ERP processes described above may include two operation modes: a streaming mode and a reporting mode. The ERP processes can operate in streaming mode only, in reporting mode only, or in both modes simultaneously. Operating in both modes simultaneously is referred to as mixed mode operation. In a mixed mode operation, the ERP at some point can stop providing the search head with streaming results and only provide reporting results thereafter, or the search head at some point may start ignoring streaming results it has been using and only use reporting results thereafter.

The streaming mode returns search results in real time, with minimal processing, in response to the search request. The reporting mode provides results of a search request with processing of the search results prior to providing them to the requesting search head, which in turn provides results to the requesting client device. ERP operation with such multiple modes provides greater performance flexibility with regard to report time, search latency, and resource utilization.

In a mixed mode operation, both streaming mode and reporting mode are operating simultaneously. The streaming mode results (e.g., the raw data obtained from the external data source) are provided to the search head, which can then process the results data (e.g., break the raw data into events, timestamp it, filter it, etc.) and integrate the results data with the results data from other external data sources, and/or from data stores of the search head. The search head performs such processing and can immediately start returning interim (streaming mode) results to the user at the requesting client device; simultaneously, the search head is waiting for the ERP process to process the data it is retrieving from the external data source as a result of the concurrently executing reporting mode.

In some instances, the ERP process initially operates in a mixed mode, such that the streaming mode operates to enable the ERP quickly to return interim results (e.g., some of the raw or unprocessed data necessary to respond to a search request) to the search head, enabling the search head to process the interim results and begin providing to the client or search requester interim results that are responsive to the query. Meanwhile, in this mixed mode, the ERP also operates concurrently in reporting mode, processing portions of raw data in a manner responsive to the search query. Upon determining that it has results from the reporting mode available to return to the search head, the ERP may halt processing in the mixed mode at that time (or some later time) by stopping the return of data in streaming mode to the search head and switching to reporting mode only. The ERP at this point starts sending interim results in reporting mode to the search head, which in turn may then present this processed data responsive to the search request to the client or search requester. Typically the search head switches from using results from the ERP's streaming mode of operation to results from the ERP's reporting mode of operation when the higher bandwidth results from the reporting mode outstrip the amount of data processed by the search head in the]streaming mode of ERP operation.

A reporting mode may have a higher bandwidth because the ERP does not have to spend time transferring data to the search head for processing all the raw data. In addition, the ERP may optionally direct another processor to do the processing.

The streaming mode of operation does not need to be stopped to gain the higher bandwidth benefits of a reporting mode; the search head could simply stop using the streaming mode results—and start using the reporting mode results—when the bandwidth of the reporting mode has caught up with or exceeded the amount of bandwidth provided by the streaming mode. Thus, a variety of triggers and ways to accomplish a search head's switch from using streaming mode results to using reporting mode results may be appreciated by one skilled in the art.

The reporting mode can involve the ERP process (or an external system) performing event breaking, time stamping, filtering of events to match the search query request, and calculating statistics on the results. The user can request particular types of data, such as if the search query itself involves types of events, or the search request may ask for statistics on data, such as on events that meet the search request. In either case, the search head understands the query language used in the received query request, which may be a proprietary language. One exemplary query language is Splunk Processing Language (SPL) developed by the assignee of the application, Splunk Inc. The search head typically understands how to use that language to obtain data from the indexers, which store data in a format used by the SPLUNK® Enterprise system.

The ERP processes support the search head, as the search head is not ordinarily configured to understand the format in which data is stored in external data sources such as Hadoop or SQL data systems. Rather, the ERP process performs that translation from the query submitted in the search support system's native format (e.g., SPL if SPLUNK® ENTERPRISE is used as the search support system) to a search query request format that will be accepted by the corresponding external data system. The external data system typically stores data in a different format from that of the search support system's native index format, and it utilizes a different query language (e.g., SQL or MapReduce, rather than SPL or the like).

As noted, the ERP process can operate in the streaming mode alone. After the ERP process has performed the translation of the query request and received raw results from the streaming mode, the search head can integrate the returned data with any data obtained from local data sources (e.g., native to the search support system), other external data sources, and other ERP processes (if such operations were required to satisfy the terms of the search query). An advantage of mixed mode operation is that, in addition to streaming mode, the ERP process is also executing concurrently in reporting mode. Thus, the ERP process (rather than the search head) is processing query results (e.g., performing event breaking, timestamping, filtering, possibly calculating statistics if required to be responsive to the search query request, etc.). It should be apparent to those skilled in the art that additional time is needed for the ERP process to perform the processing in such a configuration. Therefore, the streaming mode will allow the search head to start returning interim results to the user at the client device before the ERP process can complete sufficient processing to start returning any search results. The switchover between streaming and reporting mode happens when the ERP process determines that the switchover is appropriate, such as when the ERP process determines it can begin returning meaningful results from its reporting mode.

The operation described above illustrates the source of operational latency: streaming mode has low latency (immediate results) and usually has relatively low bandwidth (fewer results can be returned per unit of time). In contrast, the concurrently running reporting mode has relatively high latency (it has to perform a lot more processing before returning any results) and usually has relatively high bandwidth (more results can be processed per unit of time). For example, when the ERP process does begin returning report results, it returns more processed results than in the streaming mode, because, e.g., statistics only need to be calculated to be responsive to the search request. That is, the ERP process doesn't have to take time to first return raw data to the search head. As noted, the ERP process could be configured to operate in streaming mode alone and return just the raw data for the search head to process in a way that is responsive to the search request. Alternatively, the ERP process can be configured to operate in the reporting mode only. Also, the ERP process can be configured to operate in streaming mode and reporting mode concurrently, as described, with the ERP process stopping the transmission of streaming results to the search head when the concurrently running reporting mode has caught up and started providing results. The reporting mode does not require the processing of all raw data that is responsive to the search query request before the ERP process starts returning results; rather, the reporting mode usually performs processing of chunks of events and returns the processing results to the search head for each chunk.

For example, an ERP process can be configured to merely return the contents of a search result file verbatim, with little or no processing of results. That way, the search head performs all processing (such as parsing byte streams into events, filtering, etc.). The ERP process can be configured to perform additional intelligence, such as analyzing the search request and handling all the computation that a native search indexer process would otherwise perform. In this way, the configured ERP process provides greater flexibility in features while operating according to desired preferences, such as response latency and resource requirements.

2.14. IT Service Monitoring

As previously mentioned, the SPLUNK® ENTERPRISE platform provides various schemas, dashboards and visualizations that make it easy for developers to create applications to provide additional capabilities. One such application is SPLUNK® IT SERVICE INTELLIGENCE™, which performs monitoring and alerting operations. It also includes analytics to help an analyst diagnose the root cause of performance problems based on large volumes of data stored by the SPLUNK® ENTERPRISE system as correlated to the various services an IT organization provides (a service-centric view). This differs significantly from conventional IT monitoring systems that lack the infrastructure to effectively store and analyze large volumes of service-related event data. Traditional service monitoring systems typically use fixed schemas to extract data from pre-defined fields at data ingestion time, wherein the extracted data is typically stored in a relational database. This data extraction process and associated reduction in data content that occurs at data ingestion time inevitably hampers future investigations, when all of the original data may be needed to determine the root cause of or contributing factors to a service issue.

In contrast, a SPLUNK® IT SERVICE INTELLIGENCE™ system stores large volumes of minimally-processed service-related data at ingestion time for later retrieval and analysis at search time, to perform regular monitoring, or to investigate a service issue. To facilitate this data retrieval process, SPLUNK® IT SERVICE INTELLIGENCE™ enables a user to define an IT operations infrastructure from the perspective of the services it provides. In this service-centric approach, a service such as corporate e-mail may be defined in terms of the entities employed to provide the service, such as host machines and network devices. Each entity is defined to include information for identifying all of the event data that pertains to the entity, whether produced by the entity itself or by another machine, and considering the many various ways the entity may be identified in raw machine data (such as by a URL, an IP address, or machine name). The service and entity definitions can organize event data around a service so that all of the event data pertaining to that service can be easily identified. This capability provides a foundation for the implementation of Key Performance Indicators.

One or more Key Performance Indicators (KPI's) are defined for a service within the SPLUNK® IT SERVICE INTELLIGENCE™ application. Each KPI measures an aspect of service performance at a point in time or over a period of time (aspect KPI's). Each KPI is defined by a search query that derives a KPI value from the machine data of events associated with the entities that provide the service. Information in the entity definitions may be used to identify the appropriate events at the time a KPI is defined or whenever a KPI value is being determined. The KPI values derived over time may be stored to build a valuable repository of current and historical performance information for the service, and the repository, itself, may be subject to search query processing. Aggregate KPIs may be defined to provide a measure of service performance calculated from a set of service aspect KPI values; this aggregate may even be taken across defined timeframes and/or across multiple services. A particular service may have an aggregate KPI derived from substantially all of the aspect KPI's of the service to indicate an overall health score for the service.

SPLUNK® IT SERVICE INTELLIGENCE™ facilitates the production of meaningful aggregate KPI's through a system of KPI thresholds and state values. Different KPI definitions may produce values in different ranges, and so the same value may mean something very different from one KPI definition to another. To address this, SPLUNK® IT SERVICE INTELLIGENCE™ implements a translation of individual KPI values to a common domain of “state” values. For example, a KPI range of values may be 1-100, or 50-275, while values in the state domain may be ‘critical,’ ‘warning,’ ‘normal,’ and ‘informational’. Thresholds associated with a particular KPI definition determine ranges of values for that KPI that correspond to the various state values. In one case, KPI values 95-100 may be set to correspond to ‘critical’ in the state domain. KPI values from disparate KPI's can be processed uniformly once they are translated into the common state values using the thresholds. For example, “normal 80% of the time” can be applied across various KPI's. To provide meaningful aggregate KPI's, a weighting value can be assigned to each KPI so that its influence on the calculated aggregate KPI value is increased or decreased relative to the other KPI's.

One service in an IT environment often impacts, or is impacted by, another service. SPLUNK® IT SERVICE INTELLIGENCE™ can reflect these dependencies. For example, a dependency relationship between a corporate e-mail service and a centralized authentication service can be reflected by recording an association between their respective service definitions. The recorded associations establish a service dependency topology that informs the data or selection options presented in a GUI, for example. (The service dependency topology is like a “map” showing how services are connected based on their dependencies.) The service topology may itself be depicted in a GUI and may be interactive to allow navigation among related services.

Entity definitions in SPLUNK® IT SERVICE INTELLIGENCE™ can include informational fields that can serve as metadata, implied data fields, or attributed data fields for the events identified by other aspects of the entity definition. Entity definitions in SPLUNK® IT SERVICE INTELLIGENCE™ can also be created and updated by an import of tabular data (as represented in a CSV, another delimited file, or a search query result set). The import may be GUI-mediated or processed using import parameters from a GUI-based import definition process. Entity definitions in SPLUNK® IT SERVICE INTELLIGENCE™ can also be associated with a service by means of a service definition rule. Processing the rule results in the matching entity definitions being associated with the service definition. The rule can be processed at creation time, and thereafter on a scheduled or on-demand basis. This allows dynamic, rule-based updates to the service definition.

During operation, SPLUNK® IT SERVICE INTELLIGENCE™ can recognize so-called “notable events” that may indicate a service performance problem or other situation of interest. These notable events can be recognized by a “correlation search” specifying trigger criteria for a notable event: every time KPI values satisfy the criteria, the application indicates a notable event. A severity level for the notable event may also be specified. Furthermore, when trigger criteria are satisfied, the correlation search may additionally or alternatively cause a service ticket to be created in an IT service management (ITSM) system, such as a systems available from ServiceNow, Inc., of Santa Clara, Calif.

SPLUNK® IT SERVICE INTELLIGENCE™ provides various visualizations built on its service-centric organization of event data and the KPI values generated and collected. Visualizations can be particularly useful for monitoring or investigating service performance. SPLUNK® IT SERVICE INTELLIGENCE™ provides a service monitoring interface suitable as the home page for ongoing IT service monitoring. The interface is appropriate for settings such as desktop use or for a wall-mounted display in a network operations center (NOC). The interface may prominently display a services health section with tiles for the aggregate KPI's indicating overall health for defined services and a general KPI section with tiles for KPI's related to individual service aspects. These tiles may display KPI information in a variety of ways, such as by being colored and ordered according to factors like the KPI state value. They also can be interactive and navigate to visualizations of more detailed KPI information.

SPLUNK® IT SERVICE INTELLIGENCE™ provides a service-monitoring dashboard visualization based on a user-defined template. The template can include user-selectable widgets of varying types and styles to display KPI information. The content and the appearance of widgets can respond dynamically to changing KPI information. The KPI widgets can appear in conjunction with a background image, user drawing objects, or other visual elements, that depict the IT operations environment, for example. The KPI widgets or other GUI elements can be interactive so as to provide navigation to visualizations of more detailed KPI information.

SPLUNK® IT SERVICE INTELLIGENCE™ provides a visualization showing detailed time-series information for multiple KPI's in parallel graph lanes. The length of each lane can correspond to a uniform time range, while the width of each lane may be automatically adjusted to fit the displayed KPI data. Data within each lane may be displayed in a user selectable style, such as a line, area, or bar chart. During operation a user may select a position in the time range of the graph lanes to activate lane inspection at that point in time. Lane inspection may display an indicator for the selected time across the graph lanes and display the KPI value associated with that point in time for each of the graph lanes. The visualization may also provide navigation to an interface for defining a correlation search, using information from the visualization to pre-populate the definition.

SPLUNK® IT SERVICE INTELLIGENCE™ provides a visualization for incident review showing detailed information for notable events. The incident review visualization may also show summary information for the notable events over a time frame, such as an indication of the number of notable events at each of a number of severity levels. The severity level display may be presented as a rainbow chart with the warmest color associated with the highest severity classification. The incident review visualization may also show summary information for the notable events over a time frame, such as the number of notable events occurring within segments of the time frame. The incident review visualization may display a list of notable events within the time frame ordered by any number of factors, such as time or severity. The selection of a particular notable event from the list may display detailed information about that notable event, including an identification of the correlation search that generated the notable event.

SPLUNK® IT SERVICE INTELLIGENCE™ provides pre-specified schemas for extracting relevant values from the different types of service-related event data. It also enables a user to define such schemas. 

What is claimed is:
 1. A method for search head captaincy selection, the method comprising: in a search head cluster comprising a search head captain and a plurality of search heads of a search environment, retrieving, by a first search head in the search head cluster, a set of captaincy qualification parameters corresponding to each search head of the search head cluster, wherein the set of captaincy qualification parameters indicates whether a particular search head qualifies to be the search head captain and comprises a preference flag corresponding to the particular search head, the preference flag comprising a static indication of whether the particular search head has been pre-selected as a preferred search head to be the search head captain for the search head cluster; determining by the first search head that it is not qualified to be the search head captain for the search head cluster based on the set of captaincy qualification parameters corresponding to the first search head; identifying, by the first search head, based on the set of captaincy qualification parameters, a second search head in the search head cluster that is qualified to be the search head captain; and transferring captaincy of the search head cluster to the second search head.
 2. The method of claim 1, wherein the preference flag comprises a static indication of whether the particular search head has been pre-selected by an administrator of the search environment as a preferred search head to be the search head captain for the search head cluster.
 3. The method of claim 1, wherein the preference flag comprises a Boolean indication of whether the particular search head has been pre-selected as a preferred search head to be the search head captain for the search head cluster.
 4. The method of claim 1, wherein the preference flag comprises a static indication of whether the particular search head has been pre-selected as a preferred search head to be the search head captain for the search head cluster based on at least one: of a physical locality of the particular search head, and a computing capability of the particular search head.
 5. The method of claim 1, wherein the set of captaincy qualification parameters for the particular search head further comprises a configuration replication status corresponding to the particular search head, the configuration replication status being based on a last interaction between the particular search head and the search head captain of the search head cluster.
 6. The method of claim 1, wherein the set of captaincy qualification parameters for the particular search head further comprises a configuration replication status corresponding to the particular search head, the configuration replication status being based on a timestamp of a last interaction between the particular search head and the search head captain of the search head cluster.
 7. The method of claim 1, wherein the set of captaincy qualification parameters for the particular search head further comprises a configuration replication status corresponding to the particular search head, the configuration replication status being indicative of whether a last interaction between the particular search head and the search head captain of the search head cluster exceeds a pre-determined threshold duration.
 8. The method of claim 1, wherein the set of captaincy qualification parameters for the particular search head comprises a configuration replication status corresponding to the particular search head, the configuration replication status being indicative of whether a timestamp of a last interaction between the particular search head and the search head captain of the search head cluster exceeds a pre-determined threshold duration relative to timestamps of last interactions between other search heads of the search head cluster and the search head captain.
 9. The method of claim 1, wherein the set of captaincy qualification parameters is stored in a data structure accessible to each search head of the search head cluster.
 10. The method of claim 1, wherein the set of captaincy qualification parameters is stored in a data structure accessible to each search head of the search head cluster and comprises a configuration replication status corresponding to each search head of the search head cluster, the configuration replication status of the particular search head of the search head cluster being based on a last interaction between the particular search head and the search head captain, further wherein the configuration replication status for each search head is periodically updated by the search head captain.
 11. The method of claim 1, wherein the set of captaincy qualification parameters is stored in a data structure accessible to each search head of the search head cluster and comprises a configuration replication status corresponding to each search head of the search head cluster, the configuration replication status of a particular search head of the search head cluster being based on a last interaction between the particular search head and the search head captain, wherein a persistent communication thread is maintained between the search head captain and each search head of the search head cluster; further wherein the configuration replication status for a particular search head is periodically updated by the search head captain of the search head cluster based on a status communication sent via the persistent communication thread maintained between the particular search head and the search head captain.
 12. The method of claim 1, wherein the retrieving the set of captain qualification parameters is performed in response to the first search head being elected the search head captain of the search head cluster.
 13. The method of claim 1, wherein the transferring captaincy to the second search head comprises transferring captaincy from the first search head to the second search head.
 14. The method of claim 1, wherein the transferring captaincy to the second search head comprises: communicating, to the second search head, a request for the second search head to initiate a captain election protocol; receiving a request for a vote for the second search head to be the next search head captain of the search head cluster via the captain election protocol; and submitting a vote for the second search head to be the next search head captain of the search head cluster.
 15. The method of claim 1, wherein each search head of the search head cluster maintains a captain-response timer corresponding to that particular search head, the captain-response timer being configured to countdown the time between a time a communication from the particular search head is sent to a current search head captain in the search head cluster and a time a responsive communication from the current search head captain is received by the particular search head, further wherein the particular search head initiates a captain election protocol when the captain-response timer corresponding to the particular search head expires.
 16. The method of claim 1, wherein the set of captaincy qualification parameters for the particular search head of the search head cluster comprises at least a flag indicative of a preference for the particular search head to be the search head captain, and a configuration replication status corresponding to the particular search head corresponding to a timing of a last configuration replication performed between the particular search head and the search head captain, further wherein determining the first search head is not qualified to be the current search head captain comprises determining either that the flag indicative of the preference for the first search head is set to false, or that the configuration replication status corresponding to the first search head indicates that the last configuration replication between the first search head and a last search head captain exceeds a threshold duration.
 17. The method of claim 1, wherein the retrieving the set of captain qualification parameters is performed in response to the first search head being elected the search head captain of the search head cluster, and wherein an election protocol to elect the first search head comprises a Raft Consensus Algorithm.
 18. The method of claim 1, wherein the retrieving the set of captain qualification parameters by the first search head comprises accessing the set of captaincy qualification parameters in a data structure selected from a group including a lookup table and a key-value store.
 19. A non-transitory computer-readable medium having computer-readable program code embodied therein for causing a computer system to perform a method of search head captaincy selection, the method comprising: in a search head cluster comprising a search head captain and a plurality of search heads of a search environment, retrieving, by a first search head in the search head cluster, a set of captaincy qualification parameters corresponding to each search head of the search head cluster, wherein the set of captaincy qualification parameters indicates whether a particular search head qualifies to be the search head captain and comprises a preference flag corresponding to the particular search head, the preference flag comprising a static indication of whether the particular search head has been pre-selected as a preferred search head to be the search head captain for the search head cluster; determining by the first search head that it is not qualified to be the search head captain for the search head cluster based on the set of captaincy qualification parameters corresponding to the first search head; identifying, by the first search head, based on the set of captaincy qualification parameters, a second search head in the search head cluster that is qualified to be the search head captain; and transferring captaincy of the search head cluster to the second search head.
 20. A system comprising: a processing device comprised in a first search head in a search head cluster of a search environment, wherein the search head cluster comprises a search head captain, the processing device being configured to: retrieve a set of captaincy qualification parameters corresponding to each search head of the search head cluster, wherein the set of captaincy qualification parameters indicates whether a particular search head qualifies to be the search head captain and comprises a preference flag corresponding to the particular search head, the preference flag comprising a static indication of whether the particular search head has been pre-selected as a preferred search head to be the search head captain for the search head cluster; determine whether the first search head is qualified to be the search head captain for the search head cluster based on the set of captaincy qualification parameters corresponding to the first search head; identify, based on the set of captaincy qualification parameters, a second search head in the search head cluster that is qualified to be the search head captain; and transfer captaincy of the search head cluster to the second search head when the first search head is determined not to be qualified to be the search head captain. 